I have a 95 LT1 w/70k. I recently had the coolant changed/flushed as as I wasn't sure if it was done ever before. It used to run at about 215 degrees, now it has progressively run a little hotter every time I drive it. It hit 247 on my last drive and haven't driven it since then til I figure this out. The resivoir(sp?) is 3/4 full. I do smell antifreeeze after I drive it, but don't see a leak. Any help appreciated.

 

Hey Gary,
I was in the exact situation a month ago. bought an 88 and had no idea if, when or what was done, One day it hit 260, smoke coming out of side vents. No fire, no over boil of anti-freeze etc.

My suggestions: change temp thermostat to a 160 or 180. flush again again, and use royal purple engine cooler, or wetter. they both claim to lower the temp by 20- 40 degree's. mid west sells another product that says 40. my oppinion these are band aides. make sure you buy the correct coolant, the red one i believe. and make sure you follow the directions on percent of mixture with the coolant additive i mentioned above. check to see the fan is properly turning on at precise temp.
in a nut shell, look into a 160 degree thermo stat, check the coolant and additive you will put in, do another coolant flush, check belts and check to see if your air filter is dirty. you might want to consider looking into a high quality air induction system.

Good luck, i am no mechanic, yet- but i hope i helped. I did these mods to my 88 vette convert. after my engine went so high i thought i smelt pot.lol especially the smoke from my engine. the smoke was my belt melting.

good luck

ron

 

Are your fans turning on?

 

Was the system burped after refilling?

 

I'm in the middle of a recent situation so you might want to take a look at the link. Properly burping is a big key but it could be more. I'm going to be pressure testing tomorrow.


http://forums.corvetteforum.com/c4-t...ad-gasket.html

 

If you are tooling along down the road with good airflow.....it could be as drastic as a head gasket blown.....

Do the fundamentals of Maintenance prior to jumping to this conclusion.....

 

You said that you checked the reservoir, but did you check the actual coolant level? Allow the engine to cool preferably overnight and remove the radiator cap.

Your description sounds as if there was air left in the system. After it heat cycles, you have to fill the SYSTEM, not the reservoir.

Once you are convinced that the system is filled and staying filled, THEN it's time to move on to things like thermostat and fan function.

Best of luck with it,
Doc

 

You said that you checked the reservoir, but did you check the actual coolant level? Allow the engine to cool preferably overnight and remove the radiator cap.

Your description sounds as if there was air left in the system. After it heat cycles, you have to fill the SYSTEM, not the reservoir.

Once you are convinced that the system is filled and staying filled, THEN it's time to move on to things like thermostat and fan function.

Best of luck with it,
Doc

 

Not a criticism....but you are so cautious....

I guess it comes from working with folks over the years.

 

I don't know what coolant was used. It looked yellowish in the resivoir. Don't know if it was burped. I had my local mechanic do it and doubt he is familiar with Vettes, but otherwise a good mechanic. Is burping something I can do? I am no mechanic, but can do simple things. Yes the fan does turn on, but not sure at what temp. I appreciate the help. Gary

 

Well here is what I found. The coolant level is full when I took off the radiator cap. I started it with the cap off. Is there more to burping it than just opening it up. The temp. kept going up. The fan came on at 235 and had no affect. I shut it down at 240. I never had a problem with it overheating until I had it flushed and new coolant added. The coolant is yellowish. Not sure of the brand used.

Any advice. Is replacing themostat a good idea. Need your help, Gary

 

Hey Doc. Thanks for the help. Please see my addition to the thread today. Maybe you can help, Thanks, Gary

 

You might have a stuck thermostat and a 160 stat will do nothing for the temp as it will always (in summer) be wide open. Install the OEM temp stat! If your fan came on and had no effect on the temp, then you need to pull the radiator and clean the junk stuck in it keeping air from flowing through it. C4's pull road debris from below and it clogs the radiator and stops air flow. Also, here is how you burp a C4. Starting cold, loosen the rad cap to the first notch, start engine and when it gets to the opening temp of the stat, pull on the throttle stop on the front of the MAF to race the engine to about 1500 rpm, remove the cap, the coolant level will have dropped, then fill to the neck, replace cap and let the idle back down. If you remove the radiator you will have to burp several times because it is difficult to get the air out of the heater core. About three burp sessions will do it. After burping, drive the car about 5-6 miles and if the low coolant light comes on, go home, let it cool down and burp it again and repeat the drive until you no longer see the low coolant light.
Needing burping isn't your problem, debris in the radiator is!

 

garyssgary,

I agree with JFB, it sounds like a thermostat (they should always be replaced whenever doing anti-freeze anyway).

Suggest only using OEM ACDelco -- should be # 131-100.

Also, what type of anti-freeze did your mechanic use?

Believe the 95's came with GM Dex-Cool -- and only GM Dex-Cool should have been put back in (with distilled water). Any other brand or type of anti-freeze will react with GM's Dex-Cool and gum-up

Lastly, regarding your fans -- starting in 95, you should have 3 fan relays on the driver side of the radiator cover/shroud -- these relays allow the fans to have 2 speeds -- so whenever one fan is on, the other fan should be on too, and with the AC OFF, they would both be running at the same speed (low speed starting at approx 228, and high speed starting at approx 236).

When the AC is turned on, they should both be running at least on slow speed (if not high speed -- based on AC pressure which is based on outside temps).

Lastly, regarding 'burping', I would offer another idea.

The system is self-burping -- assuming that there is pressure. I would suggest that when cold, make sure coolant is up to the bottom of the cap recess, start, top off, cap (within 2 minutes), then cycle rpms from 3k to idle in 60 second intervals for a few minutes -- watch temps -- if ok, take for a drive, should be ok... However, it can take 3-5 full warm-up/cool down cycles for everything to mix and stabilize -- so check overflow tank (by bumper) daily and if cold, the black surge (pressure tank by windshield) too.

 

Ron, nothing against you at all mate, but a few things you said in there are completely untrue and just as completely pointless. Im very direct, people that knew me from years gone by will atest to that.

A 160*F thermostat WILL NOT stop you overheating. The stock thermostat in an LT1 is 180*F, which means it opened when the coolant returning from the radiator to the water pump reached 180*F, and yet his temps still hit 247*F. Explain to me how opening a thermostat 20*F earlier will prevent a climb from 180*F to 247*F any better? Thermostat changes are VERY over rated. The coolant in the LT1 flows in reverse of a normal small block Chevy V8, and it does not pass through the intake manifold. Having said that, the coolant will pass through the heads then into the block, then out, which potentially means cooler head temps, higher bore temps which translates to cooler intake charge and less bore friction.

Use the correct factory original thermostat with confidence. The difference in going to 160*F is not worth the money and youll never feel it.

NO NO NO!!! They did not use DEX-Cool til 1996.

There is NO GOOD REASON AT ALL to use DEX-Cool if your system was not factory filled with it and continually serviced with it.

Use and TRUST Valvoline GO5 or Castrol coolants in their concetrate form, mix it yourself to about 45-50%.

The main reason for water pump failure on LT1s is due to LACK OF PROPER SERVICE. GM saw fit to pour in sealing pellets which also act as a water pump seal lubricant, and YOU SHOULD ADD IT TOO. If you dont, youre not servicing the system the way it should be serviced, and youre failing to correctly maintain your cooling system.

Next on the list is heater cores, and the biggest reason they fail so often in Corvettes has nothing whatso ever to do with their design or the way they are fitted within the vehicle, ESPECIALLY on LT1s where the coolant flows through the heater core at all times. They fail prematurely due to people failing to properly main their cooling system, neglecting the cooling system by not bothering to change the coolant, and also lack of common sense when it comes to mixing the correct amount of coolant in order to help prevent corrosion.

Starting with a mix of 45-50% coolant mixed with water ( to all those saying use some sort of "special" water, ive never used anything other than tap water, and NEVER had a cooling system failure, so use whatever water you like, its all wet) gives you a good head start to keep the system in good balance, as the good quality coolant concentrate has plenty of anti corrosion properties that DO work, as do the pellets.

If you follow those steps, as well as the facts posted by a few of the people above, your cooling system will be healthy and happy for a very long time. Anyone else that wants to argue any of my points, do so at your own risk, cause ive done my homework.


Cheers blokes

 

Thanks for the help. I burped it and all was right. Guess it must be the thermostat. Like I said, I had it flushed and the problem occured after the flush. Could something of gotten plugged?
By the way, this forum is awesome. So much knowledge. I never dreamed of the other enthusiasts out there who take pride in their Vette.

 

with some of what 'casethecorvetteman' said, but have noted exceptions above in red...

 

No worries mate, i wasnt aware of that TSB, and i never stopped using something simular, i didnt ever use the GM product, i used to use Bars Leaks i think it was called (ive sold all my cars and dont currently own one, so ive gone abit rusty with some product names), id have to go through all my stuff to see what its called exactly. I never had an issue with it, but the main reason i used it was the fact it is indeed a water pump seal lubricant.



Youre correct, i had a small important part of that back to front.

 

Casethecorvetteman,

It's all cool -- great teamwork...

it's all for the love of cars and their challenges...

as always a pleasure ---

 

No worries mate, i believe i do remember you from years gone by. Seems im getting a fair few "Welcome back" messages from alot of people i didnt really know before.

to you too bloke