Hi guys, it's The Kid again.

OK, so I took the rad to a rad shop (a reputable place that a friend swears by) and told them the story. They flushed it and pressure tested it and said that the rad was absolutely perfect. In fact, the technician conducting the test owned an '88 Corvette coupe and he said that even HIS rad wasn't in as nice a shape! I even took a jar of the coolant that came out of the rad when I drained it last night, and they said that it looked fine (no trace of oil).

For my next step, I think I am going to take Frizlefrak's advice and pull the lower rad hose. I changed the upper hose when I changed the thermostat, but I didn't change the lower one (even though I bought a new one anyway - I guess I just got lazy). Funny thing is though, I don't think there is a spring in the lower hose. There doesn't seem to be one in the lower hose that's on the car, and I'm positive that there isn't one in the new hose I bought (there is that plastic braiding on the outside though...). I know that the upper hose has a spring in it. Does anybody else have a spring in their lower rad hose? If so, then I'll hit the dealer tomorrow and pick one up.

Mika:

I didn't think about the cat. But the car had an emissions test done on it a couple of years ago, and it passed without any problem, which would lead me to believe that the cat is probably fine. And I don't think there's any other blockage in the exhaust - the exhaust pump's out of the tail pipes nice and strong. But I will keep that in mind as I continue my diagnostics. Thanks for the advice.

A buddy of mine suggests pulling the thermostat out and trying to run the car without it. His reasoning is that if the thermostat is eliminated and the car still overheats then there's a good chance it's a blown head gasket. If the car operates normally without overheating then it's obviously the thermostat that was the problem (which I would have trouble believing 'cause it's a new 'fail-safe' unit that's supposed to fail in the open position). Any thoughts on this idea?

Keep the tips coming - I'll keep you all posted as I progress.

 

I don't think you should run without the T stat unless you install a "blanking sleeve". I don't know the details (someone else will likely fill in) but I think the circulation isn't right without it and you will still possibly overheat. I would also bet $$ the suggestion of the collapsing lower hose/spring is spot on. Keep at it and you'll be ready for Wasaga Beach.

 

Just had to run out and check my 89...the upper radiator hose has an anti-compression spring, the lower radiator hose does not. Is that right...don't know but it does not make sense to me...that is just the way mine is. Once the car is up to temp you should be able to squeeze the upper radiator hose and feel the surge as the thermostat opens and the pump forces water in. May seem silly but I know that you can put the thermostat in upside down...make sure you have it right side up. I personally would not run without the stat in. You should be able to get a new stat for <$10 just to make sure you have a good stat. As to the blown gasket...wouldn't the white smoke continue...honestly don't know...just wondering.

 

My '88 overheated so bad I had to shut off the air conditioning. I couldn't sit in traffic without it hitting 250 easily. Turned out I had about half the leave off of a tree stuck between the 2 radiators and a dead bird. Still can't figure out how the bird got there. After I cleaned out the trash, it cured the problem immediately. Hope this helps you. :seeya

 

Is your air dam under the radiator damaged? If it is ground down or bent rearward it may not get enough air when cruising.

 

DOH!! I may have the upper and lower thing bass ackwards as to which one has the spring. Lemme check my car and get back with ya....

 

merrick is right, if the air dam is missing you won't get the proper air flow up into the rad intake.

 

Dude...there can only be so much wrong here...this is not rocket science.

Go to a parts store and by a cheap compression gage. Remove all spark plugs, then record the pressure for each cylinder with the compression gage.
If all are within 10-15 PSI, you do not have a head gasket problem.

Definitely put a hose spring in the lower radiator hose. This is needed because the lower hose is the suction hose from the radiator to the pump, and is prone to being sucked to the point of pinching itself closed....thereby causing overheating at RPM.

 

This is not entirely true I had a blown head gasket between two cyl's (4 and 6)and the pressure dropped only 10 PSI, so.... Also I had a bad water jacket on the other side of the motor that allowed the coolent to pass the fire ring in the head gasket (this for me was on the #3 cyl). This cyl had the same PSI as all the good cyls 150-152.

 

Alright I'm back...

Sorry for not writting for so long, but I finally got the lower rad hose off of the car.

And I really wish somebody would have warned me about what a pain in the "you know what" job that was going to be! I'm just hoping that the new hose goes on easier than the old hose was to take off.

After pulling the hose off of the car, my dad squeezed it and said that it felt softer than the new one. No surpirse really - lord only knows how old that hose is. I slipped the braiding off and cut the hose along it's length to see inside. The inside top half of the hose (leading to the waterpump) was full of small cracks, while the lower half looked fine.

I still haven't put the new hose on the car yet - I'm going to pick up some new hose clamps and a new serpentine belt (seeing as I had to take the belt off to get the hose off, I figure I might as well). Once I get the new hose on, I'll put everything back together, fill the system (again) with a 50/50 mix and cross my fingers.

I'll keep you all posted.

Wish me luck.
:rolleyes:


[Modified by TheCorvetteKid, 9:28 PM 5/12/2002]

 

Your symptoms are consistant with a head gasket leak from combustion chamber to coolant. This could be a crack or gasket / warp. Could also be any number of other things mentioned on this string.

You never mentioned if the old lower hose had the spring. BTW, I had bad luck with two different aftermarket lower hoses (Goodyear, Gates) and finally bought a GM which fit correctly on my 89 (fit problem not overheating problem). GM also came with the spring, aftermarket did not.

I would borrow a coolant system pressure tester and bring that system up to 15 lbs and see if it held. The compression test is also a good idea, might try a few squirts of oil in each cylinder to reduce bleed down and see how each cylinder holds compression (as well as how much).

Also you can run without a thermostat, you do not need restriction in the system for cooling.

BTW, when is the last time you replaced the pressure cap? If it's leaking just a little it will lower your boiling point quite a bit (pressure is almost all of the increased boiling point, AF just adds a few degrees). If the coolant boils, you loose all cooling effectiveness. Unpressurised coolant will boil below 220*, even with that mix you had in there (I don't think you need a drop above 50/50).

Pressure test, compression leak down test.

Good Luck,

Pete

 

Hi PeteL

You (and the several over's who've suggested it) are probably right. It probably is a head gasket problem. I just don't want to start tearing the heads off of the car without first making my way throught the small (read cheap) stuff.

As for the lower rad hose, the new one I bought is a GM unit. In fact, everything I buy for the car (right down to the coolant itself) are GM only, with the exception of the oil which is Mobile1. In fact, if GM sold fuel, I'd get it from them too... I'm not worried about the hose fitting properly - just about it's installation (it's really really REALLY cramped in there!).

And no, there is no spring in the lower rad hose either. Neither the old one that came out of the car, nor the new one have a spring. I know that the upper hose has one, but the lower one doesn't. The lower hose does, however, have a plastic braiding outside, but now spring. If your car has a spring in the lower hose, please let me know and I'll visit the dealer before I bolt anything back together.

And the rad cap was actually the first thing I had changed. It was about $10 from GM and it was the quickest and easist part of the cooling system to change.

I thought about the idea of running without a thermostat in the car, but I don't think it would do any good in my case. The thermostat that's in the car right now, appart from being brand new, is a 160 degree Failsafe unit (which should fail in the open position) with two 5/32" holes drilled though it (as suggested by the good folks at TPIS). Even if the thermostat has, for some mysterious reason, gone bad and has failed in the closed position, it still won't offer much resistance to the flow of coolant (there's still a coolant bypass too). So I don't think running without the thermostat will make any difference.

The coolant pressure test sounds like a good idea. Any ideas on how much is the pressure tester is? Can the test can be done at home? If so, I think I'll give it a shot once I get everything back together (within the next day or two).

Thanks for the advice, I appreciate it.

And if you (and anybody else following this post) can check the lower rad hose on your cars to let me know if there's a spring inside, I appreciate that too. I'm not far off from putting the new lower hose on, so I'd really like some info before I try to get that hose back on.

Thanks again.

P.S. Merrick had asked earlier if the airdam under the car was damaged or missing. It is bent slightly rearward, but it's been like that since I bought the car over 4 years ago and this problem is relatively recent. I'll probably change the air dam anyway, but I don't think that's the problem. I will keep it in mind though.


[Modified by TheCorvetteKid, 4:23 AM 5/13/2002]


[Modified by TheCorvetteKid, 4:27 AM 5/13/2002]

 

Most of the chain stores in the US will lend you a coolant system pressure tester. New a cheap one is under $50 US. Harbor Freight has them for much less once in a while, but I just borrow one from AutoZone.

I'm pretty sure on the lower hose spring. It was a year ago, but I remember pulling the spring from the stock hose and putting it in the Gates hose, then the GoodYear hose. Then bought the GM hose and it had the spring and it fit, which the others did not. Yeah, the GM hose also had the cover. I will check the car tomorrow to make sure for you, as I my memory could be wrong.

Call autoparts stores, find pressure tester to lend!

Pete

 

YES, the lower rad hose is definitely supposed to have a spring; as mentioned above it is necessary to prevent collapse under high rpm suction from the water pump.

The upper hose shouldn't have one; seems somehow your spring got swapped! Previous owner mistake??

 

Merrick has a very good suggestion. My friend's '87 'vette and my other friend's 96 Trans-Am used to overheat a lot... until they both discovered that one has the air dam damage and the other one is missing the center section. They replaced the air dams and voila! No more high speed heating problems.

 

Hi again everyone, it's The Kid...

I apologize for the late response to this discussion string.

OK, here's what's happened so far. I've replaced the lower radiator hose, and put everything back together. I've used a 50:50 coolant/water mix and filled the system following the advise of Corvette0096 (as per an earlier posting above). I started the car and turned the heater on full-blast (again, as per the advise of Corvette0096). This is where things got interesting. The car seemed to idle fine, and there was no white smoke coming out the exhaust. The temperature (slowly) came up to normal (about 107C degrees) and the primary fan came on without a problem, dropping the temperature down (to about 95C degrees). My father suggested that I take the car around the block for a quick spin just to make sure everything was OK. I got maybe 200 feet from my house, and the temperature started to climb, hitting about 115C. As I continued around the block, the temperature began to fluctuate - first dropping to about 107C, then climbing to about 120C. At no time did it drop below 107C. I pulled into my driveway, watched the temp guage to see if the temperature would come down, but it didn't so I shut the car off. It's sitting in the driveway now, and I'm waiting to let it cool down to check the coolant level (while the car was warming up, the LOW COOLANT light was on, but once the car hit about 60C degrees, it went off and never came back on).

So let's recap everything I've done up to now:

1. Replaced thermostat with 160 degree 'fail safe' unit (with two 5/32" holes drilled through as per TPIS Insider Hints recommendations)
2. Replaced both rad hoses with new GM parts
3. Flushed and pressure tested radiator
4. Replaced radiator cap with new GM unit
5. Cleaned debris from between radiator and A/C condensor
6. Checked that both primary and secondary fans are operating correctly
7. Filled cooling system with 50:50 coolant/water mixture

The only thing I can think of now is either a blown head gasket (although there is no evidence of it in either the exhaust or the engine oil right now), or the ignition timing (the service manual suggests that an overheating condition could be a result of the ignition timing being too retarded). I'm going to wait for the car to cool down so that I can check the coolant level. Then I'll check the timing and see what that turns up.

But I'm still stumped. I'm willing to listen to any and all ideas at this point...

Thanks guys. I'll keep you all posted.

Oh, and in case anyone was wondering - no, the car did not make it to my cousin's wedding. And although it turned out fine 'cause he able to get a second limo in time, I did get ALOT of questions from friends and family regarding the car.

This is the first time the car has let me down, and it is not a good feeling.

 

My buddie's '79 was doing the same, and i think he went through all the things you have tried also. When all was finished and his car was fixed, it was a timing problem.

Under acceleration it would not advance, or retard, which ever it is supposed to do. As i am no mechanic, and can't offer much help, other than his exp that he shared with me.

 

Hey gang, I'm back.

This is really getting bad now...

OK, I let the car cool down completely. I took the rad cap off and found that the coolant level had dropped a fair bit. This was expected. I topped up the system I then had my brother start the car and hold the revs at about 2000 rpm so that I could 'pack' the system with coolant as described in the service manual. I then pulled the car back into the garage to check the timing advance. I disconnected the ESC connector, hooked up the timing light and aimed at the harmonic balancer. It showed approximately 7 to 8 degrees advance - the spec is 6 degrees BTDC. 1 or 2 degrees advanced is OK - I was looking for something like 8 or 10 degrees RETARDED! So it looks like the timing is OK.

Now this is were things get bad.

I disconnected the battary to erase the ESC error code. Reconnect it and fired the car up. Everything seemed OK for a short time - no LOW COOLANT lights, temperature increasing normally, etc...except for the LARGE amounts of white smoke pillowing out the exhaust! As I mentioned before, this smoke has happened before and it does not have a sweet smell to it - it is a very stale, irritating smell which I think is from the old fuel and water in the tank (see my earlier posts). The cooling fan came on as normal and dropped the temperature. I decided to give it one more drive around the block. This time, the smoke out the exhaust just continued as I drove (although it wasn't near as bad as when it just sat idling). The temperature also climbed to above normal levels - but it only reached about 115C degrees before I got back to my driveway.

I'm going to wait for the car to cool down again and see if it takes anything from the overflow bottle. If it does, I'll pull the rad cap and see if the level has dropped again. If so, then it's almost certainly a head gasket problem - why else would the car be loosing coolant? Just to be safe, I'll also try the "remove the plugs and crank it over" test to see if coolant comes out of the chambers.

But I am SERIOUSLY stumped here guys. I'm really close to calling a flat-bed tomorrow. Especially now that the weather is getting really nice around here - that car sitting in my garage is almost a crime! Not to mention that she's got to get an emissions test done this year too...

Any more advice? Anybody recommend a good Corvette mechanic in the Toronto, Ontario area?

Keep the responses coming.


[Modified by TheCorvetteKid, 11:31 PM 5/26/2002]

 

There is a thread on this problem from 2 weeks ago, do a search on Marcho Polo and head gasket.

When cool remove pressure cap and start engine, you may need to bring up the level so you can see it. Look for bubbles and sludge. Pull all plugs and look for coolant. I think the common cylinder is #7 but could be #8 don't remember.

Everything you have posted is still consistant with a crack or head gasket problem. Compression test would tell a tale I think.

You said you did a coolant system pressure test, what did it do? Could you hold pressure?

 

My 85 has a spring in the lower and upper hose........just replaced them and had to transfer the spring from the old hoses to the new. did you get a spring for the lower hose?