Oil Temp at 250 Deg & Brake Light came on again

[1981]

While running to Houston I started noticing the difference in temps between my Engine Temp gauge and my Oil Temp gauge. While cruising at about 60 mph the temps where steady at about 200 Deg. But when I would get up to about 75-85 mph the Oil temp would move up to about 250 Deg. Is this normal, or do I have a cooling problem?

I have an Automatic.

And then my Brake Light came on again. About 3 months ago it came on and I had to replace the left rear caliper. These are all new ACDelco stainless, the brake lines and all. Whole system was replaced about 3 years ago. Why would they be going out like this? Excessive heat? But from where? My pads are thick with hardly and wear.

Checked my master cylinder, full fluid both front and rear, and all was well. Checked all brake calipers for leaks, nothing. But the light stayed steady most of the time, and I lost hydraulic brakes. The brakes are sluggish and the car takes way too long to stop. Also that cool little hunkerdown the car should do at stop lights when put back into gear does not happen. A sure sign of failed brakes.

Any ideas on where to start first with the Temp and the Brake light?
1981

 

[jackofalltrades]

There were some questions similar to this on NetVettes recently. I don't have a computer controled Vette, but I remember some posting that the issue was really with the charging system. The temp display and other possible false indications were due to bad signals.

Don't know if that's your case.. Couldn't hurt to follow that up.

 

[Bob Chadwick]

Doesn't appear you have addressed the source of air being introduced into the brakes. It could be something else, but if I understand things correctly, there are two common sources of "pumping" of air into the system. One is the rotors. The other is the rear bearings. If they are not within spec they will cause the rotor to wobble, causing the caliper pistons to pulsate and suck air into the brakes. This can be solved to a certain extent with the replacement of the lip style seals around the caliper piston with o-ring seals, though ultimately you need to repair the source of the problem.

You indicate you have stainless calipers but don't indicate what kind of seals were used.

 

[jackofalltrades]

Guess I didn't read the brake issue well enough. I was going on the premis of faulty indicators. Now that I read more carefully, There's multiple things happening here.

I see time and time again, people replace calipers, rotors and pads. That's a brake job. Right?..

NOT, I dont' see mention of a new master cylinder. A very possible air inlet.

As for the cooling, I'd say you're at least on the edge of having a cooling problem if the indications are correct.

 

[Bob Chadwick]

NOT, I dont' see mention of a new master cylinder. A very possible air inlet.

Possibly a master cylinder but more likely another source of air. Master cylinder generally pumps up and then slowly fails. Not the symptoms being described.

 

[1981]

My brakes do not pump up. Meaning if I pump my brake pedal the pedal does not get harder to push down. Which to me would mean there is no air being introduced into the system, I guess.

The master cylinder and Booster are new, about 3 months old. This was replaced first by my mechanic then the left rear caliper. Since the master cylinder did not fix the problem I did not mention it earlier.

The seals, man I wish I new, I really have no idea. Is there a way to check?

Could the air filter line be clogged to the booster?

I really hope it is not an underlieing problem with the bearings or the rotors. So if the rotors are warped this could cause the calipers to pulsate like you described. Probably would be just one rotor? maybe the left rear, I need to check this. Man I had other projects for the vette lined up this weekend!

1981

 

[ScottRogers]

1981

I hope that your oil temp. gauge is wrong, because if it isn't I would say that your motor is not going to live much longer. That oil temp. is too high.

 

[1981]

What would cause my oil temp to be so high?

 

[1981]

And what is normal for oil temp?

 

[1981]

Filter is fine, I took it off and blew through it. I also hit the brakes with the filter off and heard the whoosh of air through this line. I guess this works OK.

I then put the filter back. And took the master cylinder top off, slowly hit the brakes and the fluid shoots up about an inch. I guess this works.

Any suggestions?
Thanks,
1981

 

[arrio]

"I then put the filter back. And took the master cylinder top off, slowly hit the brakes and the fluid shoots up about an inch. I guess this works."

I don't think there is suposed to be any shooting up of the fluid in the master cylinder. This indicates to me that presure is bleading by the piston and back into the resivour. Could be why there is so little effectiveness in the brake system.

 

[1981]

new symptoms

Now during start up the light goes out, but when I press the brakes the light comes on when the pedal is all the way to the floor. When I let up the light goes out! The brakes do not pump up, and still feel as is hydraulic is non operational.

Any ideas?

1981

 

[1981]

Please take a look at this picture & let me know if the Temps I am getting are normal or if I have an engine cooling problem. I really do not want to hurt my engine, since it was rebuilt not long ago.

Engine & Oil Temp Gauge Picture

Thanks for the knowledge,
1981

 

[21again]

My '81 is exactly the same as yours. If I drive it 55-60mph the oil temp is around 200-210. Once I get it around 70+ it will go straight to 250. What RPM's are you running at while going 70? If I remember right mine is around 2000 at 55, but at 70 it's 2500-2600.

 

[DDLS3]

I think that your oil temperature is fine. My 81 runs nearly exact to what you have described. The engine oil retains more heat (due to lack of a cooler) than your coolant. Your brake problem sounds all too familar. I believe, like as has been mentioned, that you have accumulated air in the brake system. Try bleeding your brakes, that will tell the story. If there is air present then you will need to find the cause. Like has been said, it is most likely a rotor out of true, or a worn bearing causing the caliper pistons to pulsate and introduce air past the seals into the system.

 

[1981]

Hearing this about the oil temp makes me feel better.

My brakes have a bad left rear caliper I believe due to the rotor or bearings. I will know tomorrow.

Took a trip 3 months ago to Galveston (250 miles one way) and this caliper went bad. Replaced it along with a tore up U-Joint at this wheels spindle.

Took a trip to Houston last Thursday (200 miles one way) and this caliper went bad again. U-Joints are still good, Spicers are nice. I will be looking at the rotor and bearings before this next caliper is destroyed.

I think on the highway with the caliper pulsating for 3-4 hours at 80 mph may not be good for the seals.

I also knew this wheel to make a "shick, shick, shick" sound at equal speed to the wheel's rotation.

Thanks,
1981