Isn't it amazing that when new, these cars used 50/50 antifreeze, and ran fine with little at all heat issues. Now, 30 years later, they need water only, water wetter, or chickens feet to run cool. If it is overheating, it's a bad radiator, or it's detuned, or something else simple................

 

1. You probably do not have a timing problem. You absolutely do not have a vacuum advance problem. The L81 had computer controlled advance. Stock, the baseline was set to 6 BTDC. I run mine between 12-14 with a computer chip that brings it in sooner than stock with no problems. there is no vacuum advance on an L81.

2. Yes, the stock system worked 30 years ago. Then guys like me rebuilt and re-tuned and our +/-400 hp engines would make temps rise at high RPMs. I found Water Wetter and no anti-freeze kept the temps down without the need to replace any stock cooling system components.

3. Yes, check your fan clutch as suggested above.

God bless, Sensei

 

1) Your stronger baseline helps it run cooler as much as anything.
2) Stock is 190 HP. If you double the HP, why not just increase the radiator capacity to dissapate the additional heat generated?

 

Aren't you assuming he never leaves Mesa Az.? Maybe he might want to leave the city occasionally?

 

Let's see:

New radiator $200-$600. Installation 2+ hours

Water Wetter $15 (2 bottles). Installation minutes

Hmmm?

 

If you can't get an accurate temp reading of the radiator outlet temp with the ir gun, try shooting at the inlet of the water pump at the lower hose connection. You should be able to aim at that.

Your next steps

1 Take out the tstat and test it, although from what you have said so far it seems it is working properly.

2 Then jack up the car, and remove the 2 block drains. It will show the condition of the inside of the cooling passages. See if there is crud there. So many engine flushing products and methods are not nearly adequate.

If you are running hot at highway speed it is NOT your clutch fan.

So far I'm betting on the radiator, but you need to keep testing to be sure.

No matter what you do, DO NOT flush the engine again with a new rad installed.

 

Unable to drive in half the country, priceless.
Maybe he can buy a GPS with real time weather input, so he knows where it is safe to park for the night. I wonder how much that would cost?

 

Water Wetter works with anti-freeze too.

 

Unfounded belief in snake oil (fixes in a bottle) = free.

Very very very few people claim that 'it works' and fewer still have been able to prove it.

Good luck nonetheless

 

How many miles are on the motor? PG.

 

Water Wetter is proven and backed up with solid science. The results I got are typical for use in accordance with the instructions. Of course, if you have a clogged radiator and just pour a bottle in with your old coolant mix and still have overheating...

 

I'll be checking the timing first thing tomorrow morning (I didn't get home in time tonight). Also, thanks for the heads up about the vacuum advance. That one might have left me scratching my head for a few hours otherwise....

The fan clutch checked out OK based on the testing method posted earlier.

LO PHAT

 

sorry about the vacuum advance....... forgot we were talking about an '81. D*am computer controlled stuff!

 

An 81 has a MAP sensor that tells the ECM how much to advance it per loading, so essentially, it still has one.

 

I've a got a few more comments to add here now. I've been working on the car all morning. I removed the thermostat and then reattached the water outlet housing. With a hose running clean water into the radiator, I detached the upper radiator hose from the radiator and started the car. I let the block flush for a while again, and this time I got some fairly large chunks of rust and mineral deposits blasting out of the hose.

(A side question here: Should the water have been flowing out of the hose at a somewhat even rate? I noted that the flow would stop for about 4 - 5 seconds and then water would gush out all at once. This cycle never changed, and I don't know if this would be considered normal or not.)

After I was satisfied that everything was clean and there was only pure water in the block again, I reattached the upper hose and ran the car. I could see water flowing very well through many of the radiator cores, but some of them were not flowing water at all.

(Side question #2: Should all of the passages in the radiator flow water?)

I finally added "Prestone radiator flush" to the system, capped the radiator, and ran the car for about 15 minutes. Oddly, the temperature never went past 200 degrees until I started racing the motor RPMs up and down.

So now I'm typing this while the car cools. Shortly I'll go drain the radiator and again flush the engine block with the upper radiator hose disconnected.

Any thoughts?

LO PHAT

 

You cooling system is clogged up with rust, etc. Radiator "flush" won't get it cleaned out; you need to use radiator "cleaner". You can find it in the same auto supply stores and on the same shelf as the flush stuff. Just read the label and do exactly as the instructions say (it will take a while, but the result will be worth it). Your radiator is probably "limed up" and the block may have some clumps of rust in it. That will prevent proper cooling flow. Once you clean the system and refill it with new coolant and distilled water (buy a couple of gallons at the grocery), it will work just fine.

 

He NEEDS to do the same thing that has been done for 50 years. Have a radiator shop "rod it out". They still do this, although no one boils them anymore.
Also, the white corrosion is usually from inferior solder, not calcium.The best restoration shops use 90/10 solder. China uses 50/50, and the high tin content turns to white powder.

 

This needs to be done first and then the rad rodded out.
Otherwise, all that stuff in the pic I posted above will be stuck in the rad. BTW, that stuff in the bucket was after about 4 hours of flushing not just a few minutes. There can be a bunch in there.

There is also a more dramatic method, but it is not for the faint of heart.