rainsux89

1989 L98 auto 45,000 miles. I have been chasing a coolant leak for a couple of weeks, so today(Sunday) I put some Bar's Stop leak in the rad. After a 1/2 hour of driving with normal temps, the temp gage suddenly started climbing fast, it got to 240 before I could safely pull over and shut down which was about 3 minutes driving at that temp. I had a boil over and lost a lot of coolant. I had it towed to a rad shop. Any thoughts on what happened? Could I have done some engine damage? :confused:

Marcho Polo

it's possible. The secondary fans don't even come on until 230-235 though, so you may have escaped serious harm.

Let us know what happened....

joalyons

Did you see water leaking anywhere? Did you check the oil for water or did you see white smoke or steam in the exhaust? I agree 240 is not that bad mine hit 275 when the head gasket went.

scorp508

I bet you have an air bubble in the system if you had leaks. :yesnod:

rainsux89

Hope you guys are right about the air bubble thing, it makes sense. There was no white smoke or sypmtoms from a blown head gasket. Cooling systems are not something I understand very well. Man, keep me away from tinking with motors, I'm going to ruin something. :bb



[Modified by rainsux89, 6:37 PM 12/29/2002]

VetNutJim

My 91 L98 will typically get to 250 sitting in traffic on 90+ degree days.
I'm not comfortable when it does that but it's been doing it for several years.

I've cleaned the radiator, run pure water in the summer, put 2 bottles of water wetter in it ( what a waste of 14 bux), cleaned all the stuff out of behind the condensor, cleaned the radiator fins. All of this several times.
Hasn't helped it a bit. The heck with it. If it burns up I'll build a better more powerful engine.

Turning on the AC helps cool it.
Going down the road it's fine.

240? That's not EVEN hot for an L98. Don't worry aboutit.

Sam Lam

The best method for finding a leak in the coolant system is to use a pressure checker. These are hard to "borrow", just consider it a long term investment and buy one. My 89 used to run hot....up to 240 in the summer while idling. I changed the thermo to 180 and installed a remote cooling switch. Whenever, the engine reaches 190 during idle, I just turn on the fan and she drops to 180+. The parts for the remote switch were less than $5. Regards.

Kevin 88

VetNutJim,

If turning on your A/C brings down your engine temp, then your fan is not turning on when it should. The ECM turns the fan on if it gets a signal from the A/C pressure switch, or if the coolant temp reads high enough (222 degrees). It sounds like your engine temp sensor, or its wiring, is bad.

SLO19vette91

I got a 91 vette that was just rebuilt a few weeks ago. I had noticed that it started heating up very quickly as well. Went down and picked up a new 160 thermostat and 18lb cap. Your cap could be your loss of pressure, thus causing the system to boil up faster.

SLO19vette91

P.S.

It WAS running near 250 at that point. After the 160 and cap I haven't had it over 200.

rainsux89

Well the leak is from the water pump, I expected that. The rad guy said the Bars stop leak gunked up the system and gave me a big :nono: about using that stuff ever again. $300 for the pump change, pressure flush and refill. :cuss Good thing is I told him to leave the frisbee off. :yesnod:

rainsux89

Well, $310 later I have a NEW, water pump, a temp gauge that doesn't go over 190*(it used to go over 210 on a regular basis) and no more frisbee. :D $100 for the pump, $47 for the power flush and $160 labor. He said the Bars stop leak gunked everything up and that another power flush should be done in spring along with new hoses. :bb :cuss

vetracer

I don't know what is wrong as far as your coolant leak, but I can tell you that I have overheated my '86 to 260+ more than once because of a faulty fan circuit last summer here in Arizona and it didn't appear to do any damage. As poorly maintained as the car was when I bought it (and it was running very hot for a number of reasons due to neglect) I can say that these motors can stand up toa fair amount of punishment. I wouldn't worry about it, just try not to let it happen again there is always the risk of engine damage or blowing a head gasket.

As far as keeping the temp cool, there is only two things that I have found that worked besides cleaning between the radiator and condensor and making sure the lower ductwork is intact. 1. Program your chip or put a sensor in the head to turn the fan on at 200 degrees instead of 230 degrees. 2. Buy a bigger radiator. You would be shocked to see how small the stock radiator is compared to a Ron Davis or similar aftermarket radiator.




[Modified by vetracer, 9:57 PM 12/30/2002]

qwerty111

I can't believe the temperatures quoted in this thread!

When I had my heads redone after the head gaskets blew, the rebuilder showed me the "soft" plugs in the heads that, he said, will blow out at 240-260 degrees to protect (?) the engine from damage during an overheat condition. Now I'm gun-shy and watching the temp guage all of the time.

Has anybody had any experience with these plugs blowing out? The rebuilder is a very reputable guy and does tons of work locally and off the internet, so I believe him. Is it possible that our temp. guages aren't calibrated correctly and we are getting false readings? This would be my guess.

Comments from experience Please!!

kittmaster

What about having your prom reprogrammed to kick the fans on at a lower temperature? More expensive but easier than having to monitor you temp all the time, especially in traffic.

kitt

RME1993

For the love of God, Don't ever put stop leak in your L98 Radiator!!

I did that about 2 years ago. Literally had the same exact problem. Coolant leak and my Radiator lines had a leak somewhere so I put in radiator stop leak. I drove it around a few times before my flush (which are the directions for that product of stop leak) and my coolant lines clogged up and my engine overheated and my head gaskets ruptured. White smoke coming out of the tail pipe, coolant in my oil etc. In the long run it would of saved me so much more money to just replace the radiator/lines than re building my top end to replace my head gaskets.

vette196

This is the stuff I used for a heater core leak in my Milan. The leak was too large because of the design of the heater core(angled, coolant would just sit in one area). I've heard it a very reputable product and I had nothing to lose

L98auto

Some random points to consider. It used to be conventional motor oil only began to break down around 240-250 degrees. Synthetic obviously can hold together at much higher temps. Heat is not necessarily bad. I had customers that worried when the temps approached 200 degrees. Too cold can be bad for an engine as well. The L98 was meant to run at higher temps by design for emissions and efficiency and that's straight from a GM engineer's mouth. Of course, he also admitted those higher engine temps played havoc with other underhood things like plastic wire connectors becoming more baked and brittle quicker with age. While not Bar's Leaks, GM did add a tablet form of coolant system sealer to cooling systems with they had issues with porosity in the early aluminum heads. IIRC, these tablets were even available over the counter.

xrav22

The tabs can still be had but you may have to ask the parts guy at GM to do a search.
I used 1 tab in my engine after replace of rad, h core, and thermo. I crushed it up and put it in with thermostat open. No more leaks, but not recommended if your parts are old.
Good Luck