Amur_

There is a heater core hose on the passenger side that runs above the exhaust manifold. Have you checked the hose, and its connections, for any leakage? Even just a few drops on the manifold will be very apparent to your nose. There could also be a very slight leak or poor connection on one of the coolant lines running to or from the BAC on the TB.

Have you replaced the hose that runs from the filler neck to the overflow tank?

Tomorrow night I will try to remember to pay very close attention to how my 7's 'warm up' compares to yours as you've described it...

Steel

Hmm.. answer me this..
i have an 87 car, and it has always run a bit under halfway on the temp gauge. No cooling problems ever (except a blown drivers side heating core line... but thats unrelated.)

Now my engine is running like crap. Is is because its been running a little too hot for way too long?

Amur_

Doubt it very much.

Define 'running like crap...'

Steel

"running like crap" = Crazy misfiring when decelrating, and now its at the point where it's having a hard time idling. Changed the plugs today, didnt help. Have yet to check the ACV valve. But i also have a biiiiiig hole in the exhaust, right in front of the cat iirc. Would that make my car misfire/backfire and generally "run like crap'?

powermalex

Amur
I'll check the line that feed the heater core. Any comments on the pressure build up? I'm puzzled on this. If I can solve the the pressure build up then That will solve the coolant boil over. I think the combination of the coolant expandsion and the pressure build causes the coolant to blow into tank reserve.

BobbyRX

I'm having the same problem with my car and am paying close attention to this thread.... My car has had all the hoses replaced a year ago and has approx 14K on a Mazda reman. engine. It is overheating (3/4 gauge)when I cruise at high speed And when I zip around in the city.

Would flushing my cooling system have a major effect on this or do you think its the thermostat? I have to double check the reciepts but I'm pretty sure it was replaced with a Mazda stat at the time of install...

Amur_

Judging by my aftermarket temp gauge, and assuming that our stock gauges aren't too different in their readings, then I'd guess that 3/4 on the stock gauge is 210F or more. Not desireable.

Quote:

Would flushing my cooling system have a major effect on this or do you think its the thermostat?

Flushing certainly can't hurt it. With things like this it's pretty much a process of elimination. None of us can see through steel to find out exactly what and where the problem is. So I would say do the flush, change the thermostat, etc until you notice an improvement.

Other stuff:

- when was the last time you got down and looked at the front of your rad? There may be roadkill in there or the rad fins may be clogged with dirt and crap. The rad can't do its job if air can't get to it or through it.

- do you have a copper or aluminum rad? Copper rads suck.

- most rad flush directions say to leave it in for 10 minutes. That, IMHO, is way too brief for it to do it's job. Leave it in for at least a few hours of driving so it can circulate and do its job. Better yet, leave it in for 24 hours. It won't hurt you car at all - *nothing* moves heat better than water. The 'coolant' that you add is to lube the water pump and to prevent corrosion and freezing.

- are you using Redline's Water Wetter? If not, find it in your city and start using it. I put two bottles of it in my current mix and the cooling sys is performing perfectly.

- do you have a stock rad fan? If you do, its clutch may have failed. Search the Forum for instructions on how to test it.

Amur_

Misfiring? Do you 'backfiring?' If so (it's actually called afterburn) then that's normal. Well, almost normal - it normally only happens to me when I shift at high revs. Check your anti-afterburn valve (instructions are in the FSM and the Haynes manual.)

Bad idle? Check the TPS and check for a vacuum leak.


TPS:
I'd like to add some things...

- you are inserting the probes from the mutlimeter into the back of the TPS plug. Shove them right in there 'til they're snug and not going to fall out.

- up on the plug means with the tab 'up.'

- the TPS seems to be fussy (at least it is on my 7.) Set the TPS to 1 ohm, then slowly twist the throttle linkage to fully open and then back again. Now look at your multimeter. The reading is no longer 1ohm, is it? So set the screw again and then twist the linkage again. Keep doing this until it stabilizes. And try not to take more than 2 or 3 minutes. It doesn't take long for the TPS to cool off and if it's not hot your reading will be off. If you take too long, just reconnect the TPS and take her for a 10 minute spin before trying again.

Steel

Ok... quick question concerning afterburn:

If i get a set of headers to replace all teh cats, should i get used to afterburning? and will the lack of cats now make it so that when i DO afterburn, people behind me will see? And i dont need the ACV cluster with headers and no cats either, so i can just store it for emissions day?

Thing is also, it doesnt just happen when shifing at high revs, if im cruisin in 4th at ~40 mph, then let off the gas, then pop pop. But hey, as long as it means my engine is working OK then im happy!

Amur_

An open exhaust means that you will not just have afterburn more often, but you will be throwing flames now.