Re: [MBZ] Cracked #17 head!?
Peter Frederick wrote: If it's any consolation, Volvo diesel heads do exactly the same thing, although since they have smaller valves, you can usually get them welded and they stay fixed. As far as I've been able to find out, *all* VW diesel heads (of which the Volvo diesel is an example) crack. It's just that most of the cracks never extend far enough to cause problems. I've never heard of anyone pulling a head off a VW diesel and not finding cracks between the valves.
Re: [MBZ] Cracked #17 head!?
That's been my experience (dozens), but none of them ever allowed coolant to migrate into the combustion chamber--not one. On 11/8/05, David Brodbeck [EMAIL PROTECTED] wrote: As far as I've been able to find out, *all* VW diesel heads (of which the Volvo diesel is an example) crack. It's just that most of the cracks never extend far enough to cause problems. I've never heard of anyone pulling a head off a VW diesel and not finding cracks between the valves. Casey Olympia, WA Biodiesel: '87 300TD intercooler (210k) '84 300D (205k) Gashuffer: '89 Vanagon Wolfsburg Edition (186K)
Re: [MBZ] Cracked #17 head!?
Zeitgeist wrote: That's been my experience (dozens), but none of them ever allowed coolant to migrate into the combustion chamber--not one. I had one that did, but it had been kissed by the pistons after someone put on too thin a head gasket. Maybe overheated, too, for all I know. It had wide cracks between the valves, as well as between the valves and the prechambers. I consider that an unusual case, obviously.
Re: [MBZ] Cracked #17 head!?
On Mon, Nov 07, 2005 at 05:54:26PM -0600, Rich Thomas wrote: 300D to see a 74 240D with a stick parked behind it - with a for sale Why did it have a stick parked behind it? Was Hillary in town? Oh good. I didn't miss the biannual 'eats, shoots, and leaves' discussion. K
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Alex Chamberlain wrote: Well, I just got back from dropping the car off at my indy. Spoke to the tech who had personally done the head job on it a few months ago. He remembered doing the job, but not how exactly the head was cracked---said he does too many to keep them all straight. Regarding welding the head with high-temp-safe aluminum welding rod... he said they'd tried to do that a few times with heads that only had one or two small cracks, but gave up when the welds always failed quickly and continued to leak. In his opinion the changes Mercedes made from one redesigned casting to the next were not enough to change the basic fact that aluminum is not as resistant to the stress of expansion and contraction from repeated temperature cycles as the iron head on the 617. Basically, from his point of view, all 603 heads crack; it's just a matter of how long it takes. (Although he's biased, I guess, since he only sees the bad ones.) Then he took me into the back of the shop to show me a head that he'd just pulled off a 300SDL. There was at least one hairline crack between every pair of valves, and a much wider one from one of the valves on #2 cylinder to the prechamber. Obviously toast. The casting number on it? 17. Cue spooky music. Beware #17 603 heads!!! Any head will crack if improperly installed. The revised 603 heads are fine - WHEN they are properly installed - they have as low a failure rate as OM617.95 heads! The original heads (14 and lower) were a little more likely to crack than they should have been. When they were subjected to the excessive heat load of a clogging trap, MANY (~20%) but not all failed. Even a few of the 14 heads from untrapped 603s failed, but not many (only a few percent). Once Mercedes revised the heads, they have no worse longevity than OM617.95 heads. There are 6+ years worth of 603.96 and 603.97 heads driving around outside the US and they are holding up JUST FINE! The rate of 14 heads failing NOW is VERY much lower than it was only 4-5 years ago. Marshall -- Marshall Booth (who doesn't respond to unsigned questions) der Dieseling Doktor [EMAIL PROTECTED] '87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Kevin, Isn't this the DeGroff-massaged head? (Or amI confused with someone else on that?) I can't imagine it having issues with the valve seals or guides. How bizarre! Don't sweat the higher temps - my #22 head also runs at 90-95C all the time, I long ago gave up trying to 'remedy' this. AFAICT this is normal but I can't figure why it's different than the older heads - maybe coolant passages are different in the later heads? Anyway, you need to determine where the coolant loss is occuring... make sure the rad cap is good, water pump seal isn't leaking, etc. If you didn't have the coolant issues, I'd suspect the turbo for the oil consumption. I'd sure want to rule out everything before yanking the head again... ugh... :( -Dave M. -- Date: Mon, 7 Nov 2005 14:14:07 -0800 From: Kevin [EMAIL PROTECTED] Subject: Re: [MBZ] Cracked #17 head!? (was: Portland wagon) On Sat, Nov 05, 2005 at 07:52:02PM -0700, Dave M. wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? I am curious as well. I have quite a few miles on the redone #17 head on my 87 300D, and I have this nagging feeling it's going to need to come back off. Oil consumption went WAY up, and it fits all of the symptoms of valve guide seals. The smoke out the back resembles oil in color. The oil consumption doesn't seem high enough for a blown gasket between #1 and the timing chain rail (only about a quart in 2500-3000, and this used to be a quart in 5000 car) though. Yesterday evening, I drove up the coast to cambria for dinner, and right after I lit the car off, the coolant level light came on. It went off, after a few blocks, but a peek this morning showed the coolant was low. There was some pressure in the tank too, which was somewhat disconcerting, but it was nothing like the water belching geyser that this car was with the known cracked head, and that the 87 300TD with suspected cracked head is. The car has run warm since the head was installed, instead of 80-85 degrees average, it's more like 90 degrees average, spending a lot of time around 95. It never gets above 100, even on a long hill with my foot in it, but like I said, something just doesn't seem right. K
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
On Mon, Nov 07, 2005 at 06:02:51PM -0700, Dave M. wrote: Isn't this the DeGroff-massaged head? (Or amI confused with someone else on that?) I can't imagine it having issues with the valve seals or guides. How bizarre! Don't sweat the higher temps - my #22 head also runs at 90-95C all the time, I long ago gave up trying to 'remedy' this. AFAICT this is normal but I can't figure why it's different than the older heads - maybe coolant passages are different in the later heads? Anyway, you need to determine where the coolant loss is occuring... make sure the rad cap is good, water pump seal isn't leaking, etc. If you didn't have the coolant issues, I'd suspect the turbo for the oil consumption. I'd sure want to rule out everything before yanking the head again... ugh... Joe ended up with the head, I ended up with the car :) This is a #17 from PGA that needed some work in the #1 cylinder because the cracked prechamber had actually damaged the head. That being the least of the issues with getting the head onto the car, needless to say I wouldn't give a glowing recommendation for the machinist, who was recommended to me. There being something up with the seals he placed on it would not surprise me in the least. After seeing the price for reconditioning heads through metric motors, there isn't much of a doubt that I'll just drive the next head down to LA. I didn't save any time getting it done locally. I thought there was another list member who also had problems with his valve seals, and replacing the seals seemed to solve the problem. I can blip the throttle but keep the revs below 2000 and get the blue smoke and am fairly certain that the turbo isn't contributing enough that I'll get that much smoke. I know I've got my work cut out for me with the coolant issue. K
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
The cracks between the valves are the problem. It will eventually extend into the cooling passage and leak If it's any consolation, Volvo diesel heads do exactly the same thing, although since they have smaller valves, you can usually get them welded and they stay fixed. The later heads are MUCH more resistant to cracking -- I've seen a 350 SDL with no engine work with 375,000 miles on it in for an oil change... Peter
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
In a message dated 11/7/2005 3:14:41 P.M. US Mountain Standard Time, [EMAIL PROTECTED] writes: I am curious as well. I have quite a few miles on the redone #17 head on my 87 300D, and I have this nagging feeling it's going to need to come back off. Oil consumption went WAY up, and it fits all of the symptoms of valve guide seals. The smoke out the back resembles oil in color. The Kevin, For the 603 engines, Dave M was quick to warn that not all valve seals were the same and to use only factory replacement parts. You may not have had control over the seal selected for your rebuild. I do think he said they can be replaced with the head in place with the right valve spring compressor. Regards, Jim Friesen Phoenix AZ 79 300SD, 261 K miles 98 ML 320, 138 K miles
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Dave M. wrote: Before condemning the #17+ heads, you need to know the details behind the failure (re: that SDL with a bunch of cracks in a '17.) Blowing a radiator hose and driving for an hour with the temp in the red and no coolant in the system will likely crack a #22 head also. I'm not sure if ALL cracks are indicative of a junk head; I vaguely recall that the ones from the valve to the prechamber are less of a problem than the ones between the valve seats, or vice-versa. My head had both types so I don't know which was causing my cold-high-pressure symptoms (cured with a #22 head). Many used OM60x heads will have cracks around the prechamber ports. They are USUALLY not a problem. Marshall -- Marshall Booth (who doesn't respond to unsigned questions) der Dieseling Doktor [EMAIL PROTECTED] '87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Good point, Dave. For what it's worth, though, my #17 that blew definitely did so on its own, so to speak---not because of overheating. The car overheated routinely after the head cracked, but not before, and once the head was replaced it ran perfectly again---i.e. the cooling system was NOT the culprit. Pity I don't have much maintenance history on the car. I don't know exactly when the original head was replaced, nor when the trap oxidizer recall was done. If there was an overlap, we could blame the trap for the #17 cracking. On 11/7/05, Dave M. [EMAIL PROTECTED] wrote: Before condemning the #17+ heads, you need to know the details behind the failure (re: that SDL with a bunch of cracks in a '17.) Blowing a radiator hose and driving for an hour with the temp in the red and no coolant in the system will likely crack a #22 head also. Alex Chamberlain '87 300D Turbo
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
You bring up a point that Marshall eluded to some time ago. How much head cracking was actually caused by the #14 casting and how much by the trap oxidizer that was run during the same time period? Thanks, Tom Hargrave 256-656-1924 www.kegkits.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Alex Chamberlain Sent: Tuesday, November 08, 2005 12:07 AM To: Mercedes mailing list Subject: Re: [MBZ] Cracked #17 head!? (was: Portland wagon) Good point, Dave. For what it's worth, though, my #17 that blew definitely did so on its own, so to speak---not because of overheating. The car overheated routinely after the head cracked, but not before, and once the head was replaced it ran perfectly again---i.e. the cooling system was NOT the culprit. Pity I don't have much maintenance history on the car. I don't know exactly when the original head was replaced, nor when the trap oxidizer recall was done. If there was an overlap, we could blame the trap for the #17 cracking. On 11/7/05, Dave M. [EMAIL PROTECTED] wrote: Before condemning the #17+ heads, you need to know the details behind the failure (re: that SDL with a bunch of cracks in a '17.) Blowing a radiator hose and driving for an hour with the temp in the red and no coolant in the system will likely crack a #22 head also. Alex Chamberlain '87 300D Turbo ___ For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Alex Chamberlain wrote: Good point, Dave. For what it's worth, though, my #17 that blew definitely did so on its own, so to speak---not because of overheating. The car overheated routinely after the head cracked, but not before, and once the head was replaced it ran perfectly again---i.e. the cooling system was NOT the culprit. Pity I don't have much maintenance history on the car. I don't know exactly when the original head was replaced, nor when the trap oxidizer recall was done. If there was an overlap, we could blame the trap for the #17 cracking. On 11/7/05, Dave M. [EMAIL PROTECTED] wrote: Before condemning the #17+ heads, you need to know the details behind the failure (re: that SDL with a bunch of cracks in a '17.) Blowing a radiator hose and driving for an hour with the temp in the red and no coolant in the system will likely crack a #22 head also. All heads CAN crack - even old iron heads. I've seen a small number of OM601 and 602 heads (maybe about as many as OM61x heads) that have cracked. The cracks look just like cracks in 603 heads - they crack in the same places (around prechamber and valve ports mostly). They represent a TINY fraction (1%) of the number of 601/602 heads produced (vs maybe 20% of the heads from '86-'87 603 engines). Most crack because they are abused some way. Aluminum heads expand and contract FAR more in response to heating/cooling than iron heads and because of that, require that additional measures be taken to compensate for that activity. There is evidence that aside from the heat stress of a trap oxidizer plugging up, SOME of the cracking problem resulted from the design of the head gaskets used before the the late '80s. Mercedes also redesigned the head itself - several times. A few certainly cracked because they were flawed in the manufacturing process. One problem with the introduction of aluminum heads was that they couldn't be magnafluxed as iron heads could to reveal flaws. That left pressure testing as about the only practical method for testing in the field and Mercedes acknowledges in the engine manual that even heads that pass the pressure test may still be flawed and fail once installed. Marshall -- Marshall Booth (who doesn't respond to unsigned questions) der Dieseling Doktor [EMAIL PROTECTED] '87 300TD 182Kmi, '84 190D 2.2 229Kmi, '85 190D 2.0 161Kmi, '87 190D 2.5 turbo 237kmi
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
On 11/5/05, Dave M. [EMAIL PROTECTED] wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? Good question where the crack was. I never saw the failed head---all the work was done by my indy (MBI Motors in Portland, a very well-respected shop, and I trust them that it really was a cracked head and not just a blown gasket). Sig, the shop foreman there, said that it was not the first post-#14 cracked 603 head he'd seen, either. I am seeing him tomorrow (for unrelated issues), so can ask him for details then. BTW, this was the very same 300D that you had posted about two years or so ago---the white one for sale in Sacramento with lots of suspension work, good paint, cold AC, etc. It was in great shape when I got it (and still is!), and I bought it partly because it had the #17 head and was showing no sign of cooling problems. After a few months it began to show occasional mysterious coolant loss but no other symptoms of note before the head failed catastrophically earlier this year (suddenly overheating and staying that way when driven more than a few hundred feet at a time---just enough to get it on a tow truck and to my indy). :( All better now with the brand new #22 head, of course---hopefully for good. Alex Chamberlain expensive but worth it '87 300D Turbo
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Hmmm. I think I'll keep my old #14 head that I swapped out for my current used #17 head. If the #17 starts behaving like it's kaput, I'll go get some of that aluminum welding/brazing rod and attempt a repair. The dudes at the company that sells the stuff figured it would be good for 1200 degrees F anyway. ...Kevin 87 300TD 278k mi, #17 head Alex Chamberlain said: On 11/5/05, Dave M. [EMAIL PROTECTED] wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? Good question where the crack was. I never saw the failed head---all the work was done by my indy (MBI Motors in Portland, a very well-respected shop, and I trust them that it really was a cracked head and not just a blown gasket). Sig, the shop foreman there, said that it was not the first post-#14 cracked 603 head he'd seen, either. I am seeing him tomorrow (for unrelated issues), so can ask him for details then. BTW, this was the very same 300D that you had posted about two years or so ago---the white one for sale in Sacramento with lots of suspension work, good paint, cold AC, etc. It was in great shape when I got it (and still is!), and I bought it partly because it had the #17 head and was showing no sign of cooling problems. After a few months it began to show occasional mysterious coolant loss but no other symptoms of note before the head failed catastrophically earlier this year (suddenly overheating and staying that way when driven more than a few hundred feet at a time---just enough to get it on a tow truck and to my indy). :( All better now with the brand new #22 head, of course---hopefully for good. Alex Chamberlain expensive but worth it '87 300D Turbo ___ For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Thank God for Microsoft -- Linus Torvalds
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Hi Alex, Hey, I had forgotten about that car. That is just bizarre about the head. Too bad you didn't get to see the failure, or take a picture. Glad to hear it's running well with the #22! :-) -Dave M. -- Date: Sun, 6 Nov 2005 23:02:19 -0800 From: Alex Chamberlain [EMAIL PROTECTED] Subject: Re: [MBZ] Cracked #17 head!? (was: Portland wagon) On 11/5/05, Dave M. [EMAIL PROTECTED] wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? Good question where the crack was. I never saw the failed head---all the work was done by my indy (MBI Motors in Portland, a very well-respected shop, and I trust them that it really was a cracked head and not just a blown gasket). Sig, the shop foreman there, said that it was not the first post-#14 cracked 603 head he'd seen, either. I am seeing him tomorrow (for unrelated issues), so can ask him for details then. BTW, this was the very same 300D that you had posted about two years or so ago---the white one for sale in Sacramento with lots of suspension work, good paint, cold AC, etc. It was in great shape when I got it (and still is!), and I bought it partly because it had the #17 head and was showing no sign of cooling problems. After a few months it began to show occasional mysterious coolant loss but no other symptoms of note before the head failed catastrophically earlier this year (suddenly overheating and staying that way when driven more than a few hundred feet at a time---just enough to get it on a tow truck and to my indy). :( All better now with the brand new #22 head, of course---hopefully for good. Alex Chamberlain expensive but worth it '87 300D Turbo
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
On Sat, Nov 05, 2005 at 07:52:02PM -0700, Dave M. wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? I am curious as well. I have quite a few miles on the redone #17 head on my 87 300D, and I have this nagging feeling it's going to need to come back off. Oil consumption went WAY up, and it fits all of the symptoms of valve guide seals. The smoke out the back resembles oil in color. The oil consumption doesn't seem high enough for a blown gasket between #1 and the timing chain rail (only about a quart in 2500-3000, and this used to be a quart in 5000 car) though. Yesterday evening, I drove up the coast to cambria for dinner, and right after I lit the car off, the coolant level light came on. It went off, after a few blocks, but a peek this morning showed the coolant was low. There was some pressure in the tank too, which was somewhat disconcerting, but it was nothing like the water belching geyser that this car was with the known cracked head, and that the 87 300TD with suspected cracked head is. The car has run warm since the head was installed, instead of 80-85 degrees average, it's more like 90 degrees average, spending a lot of time around 95. It never gets above 100, even on a long hill with my foot in it, but like I said, something just doesn't seem right. K
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Well, I just got back from dropping the car off at my indy. Spoke to the tech who had personally done the head job on it a few months ago. He remembered doing the job, but not how exactly the head was cracked---said he does too many to keep them all straight. Regarding welding the head with high-temp-safe aluminum welding rod... he said they'd tried to do that a few times with heads that only had one or two small cracks, but gave up when the welds always failed quickly and continued to leak. In his opinion the changes Mercedes made from one redesigned casting to the next were not enough to change the basic fact that aluminum is not as resistant to the stress of expansion and contraction from repeated temperature cycles as the iron head on the 617. Basically, from his point of view, all 603 heads crack; it's just a matter of how long it takes. (Although he's biased, I guess, since he only sees the bad ones.) Then he took me into the back of the shop to show me a head that he'd just pulled off a 300SDL. There was at least one hairline crack between every pair of valves, and a much wider one from one of the valves on #2 cylinder to the prechamber. Obviously toast. The casting number on it? 17. Cue spooky music. Beware #17 603 heads!!! Alex Chamberlain '87 300D Turbo with #22 head (whew!) On 11/7/05, Dave M. [EMAIL PROTECTED] wrote: Hi Alex, Hey, I had forgotten about that car. That is just bizarre about the head. Too bad you didn't get to see the failure, or take a picture. Glad to hear it's running well with the #22! :-) -Dave M. -- Date: Sun, 6 Nov 2005 23:02:19 -0800 From: Alex Chamberlain [EMAIL PROTECTED] Subject: Re: [MBZ] Cracked #17 head!? (was: Portland wagon) On 11/5/05, Dave M. [EMAIL PROTECTED] wrote: Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? Good question where the crack was. I never saw the failed head---all the work was done by my indy (MBI Motors in Portland, a very well-respected shop, and I trust them that it really was a cracked head and not just a blown gasket). Sig, the shop foreman there, said that it was not the first post-#14 cracked 603 head he'd seen, either. I am seeing him tomorrow (for unrelated issues), so can ask him for details then. BTW, this was the very same 300D that you had posted about two years or so ago---the white one for sale in Sacramento with lots of suspension work, good paint, cold AC, etc. It was in great shape when I got it (and still is!), and I bought it partly because it had the #17 head and was showing no sign of cooling problems. After a few months it began to show occasional mysterious coolant loss but no other symptoms of note before the head failed catastrophically earlier this year (suddenly overheating and staying that way when driven more than a few hundred feet at a time---just enough to get it on a tow truck and to my indy). :( All better now with the brand new #22 head, of course---hopefully for good. Alex Chamberlain expensive but worth it '87 300D Turbo ___ For new parts see official list sponsor: http://www.buymbparts.com/ For used parts email [EMAIL PROTECTED] To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
On Mon, Nov 07, 2005 at 02:52:10PM -0800, Alex Chamberlain wrote: Then he took me into the back of the shop to show me a head that he'd just pulled off a 300SDL. There was at least one hairline crack between every pair of valves, and a much wider one from one of the valves on #2 cylinder to the prechamber. Obviously toast. The casting number on it? 17. Cue spooky music. Beware #17 603 heads!!! Interesting. And funny thing, over the weekend, I came outside to my 300D to see a 74 240D with a stick parked behind it - with a for sale sign that had fallen onto the passenger seat. Looked a little homely, but was in AMAZING shape for a coast car - salt air is murder on cars. I had half a mind to call up on it - I've been thinking for a while now that I want something a little older, a lot simpler, and a little more rugged for a daily driver/going to work car, and use the 300D for trips and weekend duties. K
Re: [MBZ] Cracked #17 head!?
Why did it have a stick parked behind it? Was Hillary in town? --R Kevin wrote: Interesting. And funny thing, over the weekend, I came outside to my 300D to see a 74 240D with a stick parked behind it - with a for sale sign that had fallen onto the passenger seat.
Re: [MBZ] Cracked #17 head!? (was: Portland wagon)
Alex, Wow - that's one of the first, if not THE first, cracked #17 head that I've heard of. Could you give us any more details? How it happened, where the crack was (beteween valves or valve to prechamber), etc? Thanks! :-) -- Dave M. Boise, ID 1994 E500 - 95kmi (Q-ship) 1987 300D - 261kmi (Sportline) -- Date: Sat, 5 Nov 2005 17:36:21 -0800 From: Alex Chamberlain [EMAIL PROTECTED] Subject: Re: [MBZ] 1987 300TD Wagon in Portland, OR As Marshall likes to say, a #14 head on a 603 is not a guarantee of failure. But nor is a later head a guarantee of safety, as I've learned the hard way---my #17 head just cracked a couple of months ago. Now I have a #22. Alex Chamberlain '87 300D Turbo
