A BIG hill? In FL? ;<)
Wilton
----- Original Message -----
From: "Dan Penoff via Mercedes" <mercedes@okiebenz.com>
To: "Mercedes List" <mercedes@okiebenz.com>
Cc: "Dan Penoff" <d...@penoff.com>
Sent: Friday, May 27, 2016 8:13 PM
Subject: [MBZ] 300D 2.5 is Home, or Thank You Sir, May I Have Another?
Interesting would be a good way to explain my afternoon….
Went over and picked up the 300D. Other than replacing a leaky injector
return line and topping off the coolant before we left, there wasn’t much
else to do but fire it up and point it home, a roughly 30 mile trip that
is mostly interstate.
No AC, which I knew. Seems like the monovalve must be bad, as the only
thing you could get out of the ACC was heat, and LOTS of it. Fan did it’s
thing as I would expect, so the owner’s statement about the fan controller
being bad was unfounded. Turning on the AC engages the compressor and
loads the engine, so there’s definitely something going on there. It’s
still an R12 system, too, which is good. I will have to get some
different hoses for my manifold gauge set if I’m going to work on it,
though.
Car ran great, plenty of power, tracked well and braked well. Very little
smoke on load unless I really put my foot to it.
About 10 miles out, my temperature starts to rise. Hmm. It’s up to 110C.
Not good. I get to a flat run on the interstate and it comes back down to
around 90C. OK, I was climbing a big hill, so maybe that spike was from
the additional load. Temp begins to increase some more, now it’s up to
100C, maybe 105C. Interesting.
I get off the highway and am now on surface streets. Temp continues to
move up and down until we get to some traffic and now it’s about to hit
the red line. I motion to my son who is behind me that I’m heading for a
parking lot on the side of the street.
Pull in, shut down, pop the hood. I had not secured the radiator cap with
the intent that if there were cooling system problems I would avoid
pressurizing the system. Coolant is burping out of the overflow. When it
settles down I see it’s down a ways, so I add nearly a gallon of water.
Hmm. This is not good.
We hang out for a few minutes and let the car cool down.
I leave the cap unlatched and we make the dash home with the temp gauge
just tickling the red line on occasion, but not dropping much below 120C.
Ouch.
So here’s the deal, folks:
Cracked head? If this were the case, I would expect coolant to be getting
into the combustion chamber(s) and the resulting hydrolock occurring with
the expected result of a bent rod. Not likely, I think.
Bad head gasket? Probably, as this would only be failing under pressure,
meaning that it wouldn’t occur unless the engine was running, preventing
coolant from entering the combustion chambers.
Other possibilities? I would have to reach out on this one, as my
experience with diesels isn’t deep enough to identify other reasons.
It runs great, has good power, doesn’t smoke unless you really put your
foot into it. Nothing remotely indicating an internal problem that would
suggest something catastrophic is going on.
So fellow dieselers, please offer your sage advice as to what direction I
might take on this.
On a positive note, I found the receipt for a transmission rebuild in
2014, and the paint is going to clean up really well.
And yes, I’m ready for my beating. I should have looked for bubbles in
the coolant when I was running it before I took off. I saw a few, but
since it took about 3/4 of a gallon of water I just figured it was due to
bubbles from the system filling up and burping.
Dan
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