I may have missed it among all the replies, but I didn't see any mention of core plugs (freeze plug/expansion plug or whatever you choose to call them). I had a '96 that would overheat all the time. I chased the problem for almost a year. Replaced radiator, cap, had recently replaced water pump. Nothing worked and I had given up. I lost some coolant but never found a leak.
One day while doing some suspension work on the left side of the car, I noticed a rusty streak on the side of the block - under the exhaust manifold. I followed that up to a hole in the block where a core plug used to live. It was a hidden leak that must have burned off any trace of water while driving, so I never saw any water on the ground. I replaced it with one from Mazda (2 from NAPA wouldn't fit for some reason) and problem solved. On Sun, Apr 10, 2011 at 9:58 PM, bill zimmerman <[email protected]> wrote: > Now we're at the root of the problem, why did it overheat, not because of > the heater core. It may have had a bad radiator, leaking and you didn't > notice it, or it might be a bad water pump, also leaking and you didn't > notice it, either way, low on coolant and overheating. Very good chance you > have a warped head and leaking head gasket at this point, check for water > in > the oil, oil residue in the radiator, and do a compression check. Go > forward > from there, from the way you describe it I'm pretty sure you are going to > find a head gasket problem. BZ > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Bruce Labitt > Sent: Sunday, April 10, 2011 7:59 PM > To: [email protected] > Subject: Re: Diagnosing Bad Water Pump, or Heater Core or? > > On 4/10/2011 7:42 PM, bill zimmerman wrote: > > Late coming in on this and have not read other posts but if your problem > > came after any cooling system work, hose replacement, etc, make sure you > > don't have an air lock in the system, which frequently will result in no > > heat from the heater while everything else functions normally. Would not > > suspect a water pump problem if the motor is not overheating or signs of > > leakage around the pump. BZ > > > > Original problem - overheat - radiator cap let go - coolant > everywhere. Replaced cap, added water - trouble ever > since. Engine overheats. > > Could be air lock. How do you get rid of it? I used a > coolant funnel attached to radiator cap. Attempted to > squeeze hoses... Car is not level right now. Front end is > on jackstands. Problem? > > > -----Original Message----- > > From: [email protected] > > [mailto:[email protected]] On Behalf Of Bruce Labitt > > Sent: Sunday, April 10, 2011 7:22 PM > > To: [email protected] > > Subject: Re: Diagnosing Bad Water Pump, or Heater Core or? > > > > On 4/10/2011 5:25 PM, Ross Kuhns wrote: > >> If the hoses are only a year old, they should come off; > >> take a pair of slotted type pliers/grips and you can > >> usually work them back and forth a touch as you pull - > >> tool is set perpendicular to the pipe/hose. Of course > >> don't squeeze too hard, those pipes are soft. If you try > >> to confirm flow thru the core, make sure not to use too > >> much psi, system doesn't run under too much pressure (what > >> 13psi?). > >> > >> Ross > >> > >> > >> > >> On Apr 10, 2011, at 4:34 PM, Ken Bogart wrote: > >> > >>> I would flush the heater core to verify flow. If its > >>> blocked and needs replacement, a temporary bypass will > >>> certainly work to keep you on the road. > >>> > >>> > >>> Ken Bogart > >>> ----------------------------------------------------- > >>> 96 Montego Blue FFS Coldside (His) > >>> 97 Black& Tan (Hers) > >>> 90 Crystal White (sons) > >>> ------------------------------------------------------ > >>> http://www.miatacare.com<http://www.miatacare.com/> > >>> http://www.cincimiata.com<http://www.cincimiata.com/> > >>> http://www.bcchallenger.org<http://www.bcchallenger.org/> > >>> MiataMail.com<http://MiataMail.com> list owner > >>> > >>> > >>> On Sun, Apr 10, 2011 at 2:32 PM, Bruce Labitt > >>> <[email protected] > >>> <mailto:[email protected]>> wrote: > >>> > >>> I'm trying to diagnose if I have either a bad water > >>> pump, or just a clogged heater core. The hose at the > >>> output of the heater core has been spliced to insert > >>> a GM temperature sensor in the line. [Other than the > >>> temp sensor splice, the cooling system is stock.] > >>> The GM sensor is reading correctly - it reads cold > >>> and the heater line *is* cold. However, at the back > >>> of the head, the sensor which goes to the dash reads > >>> very hot (after the engine has warmed up, of course). > >>> It is as if there is no flow out the back of the head. > >>> > >>> Things I've tried: > >>> 0. Removed thermostat, put housing back. Still > >>> overheats. Have new tstat, but have not installed. > >>> 1. Remove GM sensor splice, and inspect the inline > >>> housing. Can see daylight through the hose > >>> connections. Conclusion: temp sensor housing is not > >>> clogged and not impeding coolant flow. > >>> 2. Added classic coolant flush tee in place of the > >>> inline temp sensor. Flushed 12 gallons thru system. > >>> Pretty ugly looking coolant, if I must say so. It > >>> still does not quite look like clean water, but it is > >>> far more water like than before. > >>> 3. Put back GM temp sensor. > >>> 4. Refilled with water. Installed a burp bucket on > >>> radiator, ran engine. Filled bucket 1/3 way. Bottom > >>> rad hose does not seem like it is full of coolant. > >>> Feels like it is not uniformly hot. Tried squeezing > >>> hoses, etc to burp. Not much happened with respect > >>> to coolant level. Engine heated up - back of head > >>> sensor showed quite warm - heater core loop quite > >>> cool to the touch. > >>> > >>> What I'm going to do next: > >>> 1. Bypass heater core. Is there an 'easy' way to > >>> get these hoses off? I cut them when I replaced them > >>> last summer. Are they 'welded' on by now? > >>> 2. Maybe, flush core, if above works. > >>> > >>> Anything else? > >>> > >>> _______________________________________________ > >>> Miatapower mailing list > >>> [email protected] > >>> <mailto:[email protected]> > >>> http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > >>> > >>> > >>> _______________________________________________ > >>> Miatapower mailing list > >>> [email protected]<mailto:[email protected]> > >>> http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > > Well, I didn't quite do things in order. I flushed the > > heater core. (Pulled heater hoses, attached garden hose > > with anti-backflow to one side, attached 6 foot hose to > > bucket on the other side.) Nasty, but eventually ran sort > > of clear. So it is NOT the heater core. Loads of water ran > > through it - it does not appear to be a restriction. No > > water in the cabin, either - thank goodness. > > > > Then I back flushed the head. In the water neck in the back > > of the head - out the other pipe to the heater core. > > > > Hooked everything up again. Filled through burping funnel. > > No apparent flow through the core. However, the thermostat > > is NOT installed. > > > > Is the thermostat required for the heater core to get water > > flow? > > > > I have a standard new Stant thermostat. Do I need to drill > > out the 'jiggler'? Hole size? Hole is up, correct? > > > > Is there a good test for a water pump? Looks like I'm > > running out of ideas. Carried off 50 gallons of 'water'. > > What a fruitless day. > > > > Got insight? > > > > Thanks > > _______________________________________________ > > Miatapower mailing list > > [email protected] > > http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > > > > > > _______________________________________________ > Miatapower mailing list > [email protected] > http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > > _______________________________________________ > Miatapower mailing list > [email protected] > http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower > -- "It is rightly acknowledged that people of faith have no monopoly of virtue..." -Queen Elizabeth II
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