Billz89

Hello.

It has been a month or so since I last started my 89 convertible vette. After charging the battery today, I started the car and left it to run awhile. Once I had put the charger away I noticed the engine coolant temp increasing at an amazing rate. The engine oil temp increaed too, but at a slower rate. I had turned the defroster on (when I started the car) and it was blowing cold air.

Does anyone know what could be causing this? Could it be the thermostat?

Thanks.

Bill

GlockLT4

yes, it could be the thermostat not letting the water circulate out of the engine to the radiator. I would definitely check and see that your radiator is getting hot when over whatever temp your t-stat is.

Billz89

After I shut down the engine, I opened the hood and there was a gurgling sound coming from the radiator cap. It was extremely warm under the hood; which when you consider how cold it is outside, isn't difficult to notice.

Are there any tricks to installing a thermostat? Recommended best practices?

Bill

GlockLT4

Hmm.. I don't know exactly how the L98 works to know if the reservoir gets coolant if the radiator doesn't. The t-stat is just a usual replacement. On LT1's it doesn't take long at all. I would think it's about the same on the L98. Scorp will probably pitch in and let ya know.

vader86

Well if you want to do it the right way, you can drain your radiator and clean the front of it while you have it drained. It should be caked with dirt and road debris which will make it run MUCH hotter when the warm weather comes back around. You should get a shop manual to help you remove the radiator too as it involves removing the shroud which might be tricky if you havent done it before.

Then you should take off the Throttle Body, the tstat is right below it on top of the manifold. You can replace the tstat with either a 160 or 180, dont use a new OEM part. When you put the TB back on, you can disconnect the coolant hoses going into it, as they hurt performance in warm weather.

Billz89

Doing it right is important. If I pull the cooling hoses off the throttle body, will it harm the drivability in colder weather?

I did purchase a 170 degree thermostat from Auto Zone. Whatever effort I put into this needs to be done right the first time. If I have to pull the radiator to clean it out, is there an after-market radiator that would do a better job of cooling?

Thanks.

Bill

Billz89

Oops! :eek: I tried replacing the thermostat last Saturday... I say tried as I was only able to get the top half of the bolt (at the thermostate housing) removed from the manifold. The other half peaks out maybe an 1/8" above the surface of the manifold.

It looks like the Chevy service center will be picking this car up with a flat bed. :sad:

Hopefully it won't cost me too much.

Bill


[Modified by Billz89, 5:29 PM 2/16/2002]

skidmark

I changed mine a month ago and it was pretty straightforward. Here are the steps per the shop manual; Disconnect,
Battery negative cable.
Air cleaner & intake duct.
Mass Air Flow sensor electrical connector.
Radiator cap.
Drain cooling system. (only need to remove 2 quarts at most)
Radiator upper hose.
Coolant hose at throttle body.
Electrical connector and vacuum harness at EGR solenoid.
Thermo housing bolts.
Good luck and note the position of old unit (pellet faces down), it's very easy to install upside down.

Billz89

Well, just got back the vette from the service center. After putting in the 160 degree thermo. the car runs as high as 200 degrees and the oil temp around 180 - 190. Oil pressure at idle is 32 psi.

The heater still doesn't work though. There is a 'cut-off' valve on the top heater tube and it was tightened. I loosened the valve, but still no heat. I looked for a fuse, but saw none.

When the heat is turned on, it (the fan) is slow to spin up... I think this is because the car isn't getting the hot engine coolant right away. After a minute or two, the fan is up-to-speed but is blowing cold air. It stays that way... never blowing any warm or hot air; it's always cold.

I appreciate the advice on this. The visit to the service shop was high: $401 to install a thermostat, change the oil & filter, change the tran fluid & filter. Of course, to install the thermostat they had to pull off the upper intake and throttle body then drill out the old bolts and re-tap the manifold. $269 for that.

Thanks.

Bill

Billz89

Hi Skidmark.

I finally was able to road test today the new 160 degree thermostat the chevy service shop installed last week. Here are the results:

1. The engine coolant temperature got up to 230 degrees waiting in the drive through at Krystals. The oil temp. was 225. Once back on the highway and up to speed, the coolant temp. started coming down quickly, the oil temp a little slower reduction in it.

2. The two hoses going into/out of the heater core are both hot.

3. When backing into my parking space at the house, I heard a swoosh then clunk under my dash and the sound of the air flow changed.

I'm still getting cold air out of the heating system and I'm concerned about the high oil temp. Are these normal numbers?

Thanks.

Bill

pablocruise

I can't tell ya how many times this topic has come up just this winter alone! Here's my situation from a while back: http://forums.corvetteforum.com/zerothread?id=202649
It might help, but I have a feeling it's not. There are quite a few other things to look at. Lemme know how else I can help, as I have seen a bunch of other posts about breaks in the system. BTW, these things are fixes YOU can do(if you are so inclined)and save some $ to boot! :cheers:


[Modified by 89 Paul in cal, 11:52 PM 3/2/2002]

Billz89

Hi Paul,

Yesterday morning I decided to drive the vette to work and take it to a shop to have the rear-wheel clunk investigated. That is another post that is on-going around here somewhere and it turned out to be the u-joint, driver side.

During the morning drive, no heat came out of this system. Cold air even though the heater was on and set to 90 degrees.

On the way home, the heater was turned off and it felt like it was around 110 degrees in the passenger compartment. No fan motor was blowing, but it sure was hot in there! I thought my tonsils were going to dry up and turn to powder it was so hot & dry in there.

Anyway, I didn't understand how a resistor could cause this. I do have some experience with electronics, and the best I can recall once a resistor goes, it is gone. Same for transistors (PNP or NPN), capacitors, diodes, etc.

If you could shed any more light on this one I might be able to avoid having the shop work on that part.

Thanks.

Bill

pablocruise

ok, now lemme give ya this link: www.idavette.net/tech/c4diag.htm maybe that will help shed more light on the situation. Sorry, I feel like I am making ya chase electrical gremlins at random.

skidmark

By setting the temp to 90 you will see the passenger compartment heat up
even with the heater turned off. This is because the fan runs at all times at
low speed and will try to achieve the 90 degrees you set it for even with the heater off. It sounds to me like you have a vacuum leak in the heater system. There are little vacuum controlled flaps/doors under the dash that open/close in order to direct the flow of air
according to the setting you request (heat, defrost, bi-level etc.). When you
select heat all the air is supposed to flow from the floor vents. Turn the fan on high and see if it's coming from one of the other vents (dash or defrost).I don't understand how you can get cold air from the heater and still have the passenger compartment boiling.

Billz89

Well, these are two seperate occasions... most of the time, when cold air is blowing out from under the dash.. back by the firewall ..it is cold in the passenger compartment. Every now-and-then you can turn the heater all the way up and it works, heating up the passenger compartment as you would expect. However, if you turn the heater off during that time, even though the fan isn't blowing (or isn't blowing hard enough to feel the air flowing) it is *still* hot inside the passenger compartment.

skidmark

First make sure you have enough coolant in the system. Remove the radiator cap when the car is cold, idle it up to 160 and feel the upper radiator hose to make sure the thermo opened. Look in the radiator and insure it is full, it may have air in the system from when they installed the new thermo. Also, have someone hold the idle at 2000 rpms and see if it needs more coolant. If so add enough to get it to the top of filler neck. If this is your problem you should have gotten a low coolant warning light but it's worth a try. Otherwise I would check the operation of the flaps by trying each setting (heat, defrost, economy) to insure they are all working. When doing this set the temp setting to 85, when you select 90 it causes somekind of override to occur.