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The L98 headgasket baffled me as it took SO long to make itself obvious. Usually you can tell right away
If your radiator ,heater core, water pump start seeping, or your radiator hose looks twice its diameter after you shut it off well....
Hopefully again, this isnt the case. If it is, at least give them a quick surface and not cracked (cheap to have done) Just tossing a gasket in may have you repeating this pita bit of labor.
edit:
i see above that Seabright had noted the siphoning issue. right on. you may well have a slightly blown head gasket. mine turned out to be quite small. but make sure you check the cap/hose/neck as well!
MLM0, I just went through all of this on my 85.
Just putting it all back together with a new headgasket.
Red had the first thing to check and im only repeating it because i don't think i saw that you reported it passed inspection.
your rad fluid expands when it gets hot and pressurized.
the pressure overcomes the spring in the cap, and opens up access to the overflow hose to the overflow tank.
in other words just because fluid keeps going to your overflow tank, it doesn't neccessitate the requirement that its exhaust gasses/blown hg that is forcing the fluid out. hopefully not.
anyway, when you turn the car off, the system cools off, and it SHOULD "vacuum" the fluid sitting in your overflow tank back into the rad. Its a closed system.
If it is NOT doing this, sounds like its not, then the very first thing to check, is your cap, and your overflow hose and a crack on the neck of your rad (if its plastic) right at the cap. in other words, if the system is drawing in air somewhere instead of drawing the fluid back up the overflow hose, this is yoru problem.
honestly its probably your problem.
i say that because i know it is what my 85's problem STARTED OUT AS.
but, remember, each time your get the expansion, which gets hotter each time because you have less coolant each time you run the engine, and none of it is coming back in, then this leads to a condition where you have not enough coolant and boom you overheat and blow a head gasket. I am about 95% sure this is how it happend to my 85.
When i was in the stage of the process like you are, diagnosing, I found that the EXACT same thing happening. i would fill, burp (by lifting the front end, and even better if you can lift the passenger side up even higher) and following the L98 burp procedure....even when doing that...i would have the coolant fill my overflow reservoir, i simply checked it a few times while it warmed up and i could see it filling itself.
But then when i shut if off and it cooled down, it never sucked it back in.
i also own an 87. i went over and grabbed the 87's rad cap.
put it on, and low and behold, it started to suck the fluid back in. there are two seals on the caps. in my case, the seal that seals against the top lip of the rad was old and dry and cracked and it was letting air into the system when it was cooling/de-pressurizing. obviously air flows easyier than lifting that fluid.
However, my car still had a blown head gasket in #7. My guess is that the blown head gasket was caused by this issue, and it was just never recognized.
sorry so long, hope that helps.
also, you asked if a loose intake gasket could cause it. yes absolutely it could. remember your cooling system is supposed to be a sealed unit. pressure neither enters, or leaves. so if your intake manifold bolts are loose (this was also the case on my 85) then you will have a spot where the vacuum can occur.
i am new to all of this, but im just sharing what i found with my 85.
im am willing to bet that so much of the blown #7 head gaskets we have in these cars, is because of a cap seal not sealing good enough to let the rad system suck in the overflow fluid again. which is a negative feedback cycle as next time if fills it a bit more if it gets hot enough. and eventually the car runs with not enough coolant, and you get stuck in traffic on a hot day, and boom, it overheats because there isn't enough coolant circulating and the water pump is cavitating. all your fluid is the overflow.
if parts of what i have written are wrong, im sure they will be corrected.
in my case, with my 85, even after i fixed the cap, and cut the hose down a bit to get uncracked hose at the rad overflow nipple, when i pressureized my cylinder 7, my overflow tank bubbled. which meant that the pressurized air i was in jecting was going though the blown hg at #7, into the cooling system, overcame the 16psi pressure of the cap, and out the hose, into the overflow. on my long "seeping intake bolts" thread, its all documented and video's. but its really long.
ive learned way more about the systems that operate the car than i ever thought i would. or cared to. but hey. such is the life of owning a really old but amazingly cool car.
Good info, thanks. I hope to know more Wednesday. I did compression test last week and got 150 in all 8
Did you get all the air out? I jack mine up and let it out instead of using the bleeders. Get the right cap not some generic cap. Make sure it does not have any crap in the way.
I had a very thin split in the rubber seal on the cap. Looked for two years before I found it. Changed cap and no more problems
today I checked for gasses in the coolant by using coolant tester from auto zone. the test never turned yellow did it numerous times with same results.
check coolant system pressure with tester, the pressure held great 14-15
did this several times with same results
i even left tester on and reved engine, no bump in pressure
i did notice that my over flow tank cap gasket is quite worn, and the cap will screw on, but i can just pull it off with a little tug i ordered new cap and new ones come with different gasket material instead of cork. while im waiting, i put some rtv seelant inside the cap to see if it helps after it drys
Could that keep water from staying in radiator and not going back into radiator as it cools down
I'm really confused on this problem
i still have the testers, if someone has another suggestion
Well id say your luck far out weighs the bad luck on the spring. Really, very glad to hear that it sounds like you head gasket is holding.
i dont *think* the cap on the expansion tank needs to be sealed tight.
that said, an easy solution for caps is to get a sheet of felpro gasket material and just cut new ones. its very easy. i did my rad cap and my coolant cap.
my cap is a 16psi cap. that means that when the pressure exceeds 16psi it will allow coolant to push pash the lower spring backed seal and the overflow will fill a bit.
your problem could still be between the lower cap seal and the overflow.
when the system reverses its pressure gradient, , if the seal at the too of the cap, the seal between the cap and the neck of the rad, can allow AIR in instead of sucking up the rad fluid.
i would definatley either buy a sheet of gasket (felpro black) and carefully remove the small circular gasket in your cap and cut and replace it.
some just buy a new cap.
also, check for a crack in the nipple where the hose comes off the rad. and check for a bad hase right at the nipples of the rad and the overflow tank. that will probably fix the whole "coolant exiting but not coming back in" problem.
maybe your problem is solved. but if its not and you are overheating, id check for a stuck half open thermostat next, and after that id check for a failed (but partially operational) waterpump.
good luck and report back!
Originally Posted by mlm0
i swear, if I didnt have bad luck, i would not have any at all my garage door spring just broke and i cant even open door mannualy
Bad Luck ??? Hardly - If you passed the pressure test - your Head Gasket is almost certainly OK.... I'd call that great news !!!
Hopefully a new cap on the overflow tank fixes the problem, and you can use the Vette to go to the Big Box Home Improvement store of your choice and buy a new set of garage door springs.
As antfarmer said - get a friend to help lift the door and use a vice grip along the track to hold it up. I would suggest that while you have the friend there - you disconnect the other spring - and use a bathroom scale to weigh the door - you need to know the door's weight to figure out which replacement springs to buy. Get the door up to the point that there is a little bit of slack in the cables, use the vice grips to prevent it from moving down and it's not too bad a job to put the new springs in.... Make sure to install the safety cables...
Well id say your luck far out weighs the bad luck on the spring. Really, very glad to hear that it sounds like you head gasket is holding.
i dont *think* the cap on the expansion tank needs to be sealed tight.
that said, an easy solution for caps is to get a sheet of felpro gasket material and just cut new ones. its very easy. i did my rad cap and my coolant cap.
my cap is a 16psi cap. that means that when the pressure exceeds 16psi it will allow coolant to push pash the lower spring backed seal and the overflow will fill a bit.
your problem could still be between the lower cap seal and the overflow.
when the system reverses its pressure gradient, , if the seal at the too of the cap, the seal between the cap and the neck of the rad, can allow AIR in instead of sucking up the rad fluid.
i would definatley either buy a sheet of gasket (felpro black) and carefully remove the small circular gasket in your cap and cut and replace it.
some just buy a new cap.
also, check for a crack in the nipple where the hose comes off the rad. and check for a bad hase right at the nipples of the rad and the overflow tank. that will probably fix the whole "coolant exiting but not coming back in" problem.
maybe your problem is solved. but if its not and you are overheating, id check for a stuck half open thermostat next, and after that id check for a failed (but partially operational) waterpump.
good luck and report back!
Thanks for info. Wouldn't a pressure test show a leak at the area you are talking about
Garage door is under warranty except for 65.00 deductible and it covers broken spring. My door is only one spring type, not two. Oh well? Can't do my honey do's with out use of car. Just have watch car shows all weekend
Remember, I'm the same guy who can't even figure out where my coolant is going. I think replacing spring would be way over my head "no pun intended:
While I'm here, I just wanted to thank all you guys for helping me along. With out your help I would have had to sell mr car long ago because of repair expenses
I know it's sometimes a PITA to help, but I really do appreciate it. If anyone gets to my area, I would love to buy lunch and drinks
Your not sucking it back in look at you cap to your hose in the over flow tank. Or just a rough or crappy where the cap goes. The cap on the over flow on mine is not tight either. Did you ever pull your top shroud and clean inbetween?
Last edited by antfarmer2; Apr 23, 2016 at 09:46 AM.
not if the leak is at the cap because wasnt the tester one of those jobbies that u put on the rad cap? it wont test from the lower seal upwards.
check those things and i bet u find your culprit.
Originally Posted by mlm0
Thanks for info. Wouldn't a pressure test show a leak at the area you are talking about
Garage door is under warranty except for 65.00 deductible and it covers broken spring. My door is only one spring type, not two. Oh well? Can't do my honey do's with out use of car. Just have watch car shows all weekend
this is crazy. i put water in radiator, started car up, and within a minute the low coolant light comes on. there is no way i am loosing coolant that fast. of course when i go to check the level and take off the radiator cap, water comes spurting out of radiator under pressure, so i can't tell what coolant level really was before i took off cap i have replaced coolant sensor with a new one. also replaced t-stat today. because my garage door is broken i can't take car for test drive
Does it lose coolant at any temperature? Because my radiator was cracked, right below the lower hose but wouldn't leak unless it was above 200-205 degrees. I would constantly get low coolant light and the overflow tank was always full. I DID a pressure test and it checked out just fine. Replaced the radiator and never had a problem since.
no prob, i had the same thing when i was refilling my 85.
did u google L98 "burp" coolant procedure?
thats the most likly situation that sets off the low coolant light.
btw, awesome looking c4
Originally Posted by mlm0
this is crazy. i put water in radiator, started car up, and within a minute the low coolant light comes on. there is no way i am loosing coolant that fast. of course when i go to check the level and take off the radiator cap, water comes spurting out of radiator under pressure, so i can't tell what coolant level really was before i took off cap i have replaced coolant sensor with a new one. also replaced t-stat today. because my garage door is broken i can't take car for test drive
not if the leak is at the cap because wasnt the tester one of those jobbies that u put on the rad cap? it wont test from the lower seal upwards.
check those things and i bet u find your culprit.
That was the type of tester I used. I'm not sure what you are referring to. That sounds like it could be my problem, but not sure how to check that out. Would I need new radiator?
I just haven't convinced myself that I'm actually loosing coolant. The car never over heated. It's almost like an airlock, but I can't get past it.
Another symptom I forgot to mention, if I keep rpm higher, lower gear, the light goes out. When I switch back to drive, rpm goes lower and the light will come back on. When I did pressure check, the pressure did not increase when I raised the rpm
Tomorrow I am going to drill two small holes in the T-stat to help with trapped air
