my overheating issue

[supra_man87]

hey all. good to be back. but i guess the reason im back is cause im having more issues. this time with cooling. i noticed when im driving my temp will begin to rise and fluctuate. im thinking this is a fan issue, but i have a new fan clutch on it. ill also list what else is new on it. new rad cap, new waterpump, new 160 failsafe (had good luck with it so far) t stat, and new radiator. also no shroud or under cover. but never made a difference before.

during the winter, i noticed i would have zero heat so i changed my t-stat to 180, and still no heat, so i zip tied the plunger on the vsv upward, little more heat but not much. so i completetly bypassed it. no difference with heat.

in all the car runs great. just this overheating is getting me mad. possibly the overheating could be linked to the bypassing of vsv????

i read shaef's post about over heating. http://www.supramania.com/forums/showthread.php?t=1097

1) no smoke or residue in oil. but inconsistant temps.
2) do not see any leaks but notice have to fill coolant occasionally. and upper hose was firm when i squeezed it when engine was still hot.
3)again, new fan clutch.
4) again, t stat is new. never had a problem with a 160.

hope this helps. and hope you guys know whats wrong.
thanx for helping.

[AJ'S 88NA]

160 is kind of low, I'd use at least the 180 or 195. The coolant has to be going somewere, if it's not leaking it is probably burning it. Notice any on the passenger side floor?

[supra_man87]

Yeah that has been checked too. (Thinking it was the heater core). And that's dry too.

[SupaMan]

i beleive either IJ or jet jock have said the car is in closed loop until the ecu sees 195 from the coolant.

[bishop40k]

If you're losing coolant, then it's going SOMEWHERE, your oil level isn't rising is it? no puddles under the car? have you tried to let it sit and idle and check for leaks? Also if your car is an auto, check the level of the auto fluid, you may have a leak in the radiator causing the coolant to go via the tranny cooler. As for the no heat thing, possibly clogged or dying heater core. I have been known to stick a garden hose in one side of the heater core and let the other side pour into a 5 gallon bucket a couple times.

[MadNad]

I had the same symptoms, finally bought a block test which told me to replace the HG. Sounds like you might be getting exhaust in your coolant

[jgcable]

Same exact thing happened to me. It was the HG. Basically it was slightly leaking into one of the exhaust ports and burning off. I never had a leak but the temp would fluctuate and I had to add coolant once a week. Have a leak down test done. My guess is its the head gasket.

[supra_man87]

i beleive either IJ or jet jock have said the car is in closed loop until the ecu sees 195 from the coolant.

well first off, my car is your exact twin. 86.5 white, grey leather sport package. and second, ill try a 195 and see if that helps.

no puddles with the car sitting for a long time. if anything my oil is lower, but im thinking its cause of the oil being used isnt thick enough. and tranni fluid isnt higher. and lastly every time i change my coolant, i back flush it alot.

i would think it would be a hg, but there are no signs of it. my car doesnt smell like syrup, and my temp doesnt fluctuate all the time. i could do the same thing in two identical days, and only one day it would overheat it just doesnt make too much sense to me

[bishop40k]

Hmm, any surging from the engine? try opening up your heater valve, and burping the system, probably not the fix, but worth a try.

[SupraCobra]

Sounds like a BHG.
Do you get better gas mileage now than you did before?
As for the heater core, does your heater work?
I'm guessing not since there is no coolant in the core.
Check the VSV and make sure it is allowing coolant to get to the heater core.
http://i44.photobucket.com/albums/f40/Neo197666/IMG_0633.jpg
A bypassed VSV. ---^
http://i44.photobucket.com/albums/f40/Neo197666/VSV2.jpg
VSV - Allows vacuum to open the coolant passage to the heater core.
But if the VSV is working properly then that means you are burning a ton of coolant and you do indeed have a BHG if you do, in fact, have no leaks.

[supra_man87]

the vsv is bypassed with a 90* coupler. and about the same mpg.

[MadNad]

...no puddles with the car sitting for a long time.
i would think it would be a hg, but there are no signs of it. my car doesnt smell like syrup, and my temp doesnt fluctuate all the time. i could do the ame thing in two identical days, and only one day it would overheat it just doesnt make too much sense to me

Again, I had these exact thoughts. I kept trying to solve it by checking other parts of the cooling system, until finally one day I stopped the car and had my resevoir overflow. I finally bought a block test and had to do the test multiple times as the exhaust pressure started pushing the fluid out the radiator. I never saw milk.

[supra_man87]

Ok, so I'm thinking it might be my heater core. My interrior fogged up last night. A hose blew on my way home, and fixed it, than it started smoking from under the engine bay again and the windows fogged. I'm thinking it was either the steam coming inside my car (windows were down) or my heater core blew and stem came through the heater (heater was on). So I think I'm pretty prepared to take out the dash once I get this confirmed. So I was thinking, other than cleaning my dash, what other things should I check, do, once all this is out. I'm talking like maintainance, mods (like to maybe rig the heater blower to blow harder???), or other stuff. Let me know. Thanks.

[supisarethebest]

hey guys i have dirty antifreeze,any one knows what might be causing that.I also my temp gauge goes up indicating that there is overheating going on but then it goes back to normal after a minute or so

[jgcable]

Ok, so I'm thinking it might be my heater core. My interrior fogged up last night. A hose blew on my way home, and fixed it, than it started smoking from under the engine bay again and the windows fogged. I'm thinking it was either the steam coming inside my car (windows were down) or my heater core blew and stem came through the heater (heater was on). So I think I'm pretty prepared to take out the dash once I get this confirmed. So I was thinking, other than cleaning my dash, what other things should I check, do, once all this is out. I'm talking like maintainance, mods (like to maybe rig the heater blower to blow harder???), or other stuff. Let me know. Thanks.


Before you go through all the hassle of ripping out your dashboard, what hose blew?? Also... did you ever get a leak down test done? My guess is you have a BHG. The steam is coming from your engine bay. When you put the heat on it draws air from it and the steam came in. If you heater core is blown you will have a puddle in your passenger side floor.
Get a leak down test done bro to rule out a BHG. The symtoms you are experiencing are all common to a BHG.

[AJ'S 88NA]

Have to agree, get a block test, JJ I believe said that there is a way to use a pool water test kit. Maybe He'll chime in and explain what chemicals you use out of the test kit. :)

[supra_man87]

ok so for sure its not the heater core. and its been running great lately. still dunno whats up. thinking pin hole leak in a hose.

[jetjock]

Lmao. It's the old river in Egypt thing again.

AJ: Aquarium PH test kit...

[AJ'S 88NA]

Lmao. It's the old river in Egypt thing again.

AJ: Aquarium PH test kit...

Thanks JJ, knew you'd be lurking somewere;

[jgcable]

ok so for sure its not the heater core. and its been running great lately. still dunno whats up. thinking pin hole leak in a hose.

Mine ran great too until the gasket let go. I had the same issues as you for almost a year. Get a leak down test done.

[supra_man87]

Mine ran great too until the gasket let go. I had the same issues as you for almost a year. Get a leak down test done.

leak down test has been done. everything came back negative for a bhg. oh yeah thanks ass, cause i know your "bhg denial" thread was somewhat directed at me. everyone else, like aj and jj, thanks for your help.

[jetjock]

I should have been more clear so I'll try again: he's right. A new head gasket is in your future. I can almost guarantee it...

[supra_man87]

so i found out what was wrong is that the hose from the top of the head to the heater control has a slight hole in it, so therefore it leaked on the ex manifold, causeing steam which came into my car as the heater was on, and the temp gauge is my fan clutch going bad again. i compared to to a new spare one i have and there is a definate difference. and jj, i would like to know the process on how to check the ph level with a pool one.

[jgcable]

leak down test has been done. everything came back negative for a bhg. oh yeah thanks ass, cause i know your "bhg denial" thread was somewhat directed at me. everyone else, like aj and jj, thanks for your help.


My BHGD thread was directed at everybody who posts here. Not just you bro. Mine went over the summer. I asked the same questions as you.
Has your head gasket been replaced? If so... has the head been torqued correctly? Was it retorqued? Did you use new head bolts or ARP studs?
I was trying to help you out.

[jgcable]

and another thing. When my car had its first temp spike I went into BHGD and replaced the thermostat. The temp didn't spike for almost 3 weeks after that. Then.. my hose started leaking exactly where yours did. I tightened the hose clamp and it seemed fine. Then... a few weeks later the temp spiked a few times and I did a leak down test and it had a BHG. Let me tell you.. it had a BHG all along. I was just in denial. Its my sons car and I really could have screwed him up because of it.

[3p141592654]

Your head gasket probably looks like this. It likely has a small leak between cylinder and coolant passages. As you drive, gasses leak into the coolant passage on the affected cylinder power stroke and the coolant pressure spikes, and bubbles form that hinder coolant flow. The weakest link, like that old heater hose or the small L-shaped hoses fail under the increased pressure. The bubbles cause random temporary spikes in the temperature readings as they travel around before being dumped out the overflow. As it gets worse your overflow will spew gasses and overflow onto the pavement. Most of us have been down this path. Unlike many cars, the 7M BHG starts off almost unnoticeable, and gets worse over a long time. At the start it can be so slight that block tests are passed, and denial sets in.

http://www.supras.org.nz/images/techinfo-bhg/bhg-wide.jpg

[jgcable]

exactly. I was in BHGD for almost 9 months before it actually let go. I had to add coolant occasionaly. I had an extremely minor leak between the rear water jacket and an exhaust passage. It would leak in and burn off in the exhaust but not enough to set off a full blown BHG until.. one day.. it went. Thank God for all the great people on this site to help me do the job correct. .the first time. This place is the bomb and I was just trying to help this guy. My BHGD thread is directed to everybody.. especially myself!

BTW.. the above thread was exactly what my HG looked like but mine was the rear cylinder.

[SupraCobra]

-Thank you Alex, I'll take Denial for 200.

-Anwser: 7M GE/GTE.

-What is a blown head gasket?

-That's correct!

[aus87nat]

and another thing. When my car had its first temp spike I went into BHGD and replaced the thermostat. The temp didn't spike for almost 3 weeks after that. Then.. my hose started leaking exactly where yours did. I tightened the hose clamp and it seemed fine. Then... a few weeks later the temp spiked a few times and I did a leak down test and it had a BHG. Let me tell you.. it had a BHG all along. I was just in denial. Its my sons car and I really could have screwed him up because of it.

You only changed the thermostat? Hehe, I went through pretty much the whole cooling system. I'd still be in denial, but there's nothing left to replace and loosing half a radiator a week gets a little hard to explain.

[jgcable]

You only changed the thermostat? Hehe, I went through pretty much the whole cooling system. I'd still be in denial, but there's nothing left to replace and loosing half a radiator a week gets a little hard to explain.

I know... I actually felt guilty when I put it in. I replaced the radiator cap too. I knew it was going for almost 6 months but I didn't want to admit it.