byrdman454

My nephew's '85 32v started to overheat tonight on the way home from school. It is low 60s here but temps got high about half way home. His school is not far from home. He got the car shut down and pulled off the road. When I got there, the radiator and upper radiator hose is hot. That hose is also under pressure. The lower radiator hose was cold and not under pressure. I checked the coolant and it was full, no leaks anywhere. This car has an Engine Guardian WP in it. I am guessing that the thermostat failed and will not allow coolant to flow from the engine to the radiator thus spiking the temps after a short drive. The other scenario is the impeller failed and Ed's WP saved the engine. The car runs perfect except for the high temps. Is there anyway to check one or the other or am I forced to start with the cheap solution and throw a thermostat and seals at it with my fingers crossed?

SwayBar

From your description the thermostat failed because the the hot engine water is exhausted to the lower radiator hose to be cooled.

Since that hose is cold, it would appear that the thermostat has not opened.

Mrmerlin

from the info provided the impeller on the water pump is not turning,

It is the rubber drive coupler,
for some reason the teeth dont make full contact,
thus the parts that do touch take more of the load and fail .

Best bet replace the drive coupler or put on a new Laso .
NOTE dont keep testing/ running the engine as you can cause damage to the block and heads .from warping

The Forgotten On

I had the front seal of the thermostat fail and cause the same issue, temps went up fast and blew my water bridge gaskets in less than 5 minutes.

The part only cost me like $2 but it cost me $20 in the end with the other seals, tstat, etc. and a lot of my time.

I recommend replacing the thermostat and its seals and seeing if that fixes the issue. It couldn't hurt.

Bertrand Daoust

It could be the thermostat or the coupler on the pump.

Easy thing first.
Remove the thermostat and test it.
If it's not working like it should, put in a new one (83 C) and related seals of course and go on.

If it's working like it should and if it has not been changed recently, change it while you're there and go to the WP to inspect the coupler. You don't need to remove the pump to do this. Just remove the cover on the pump itself.

How old is the coupler?
How many miles on it?

If it's the coupler that let go, then look if the impeller/shaft bearing is seized. If it is seized, the GP saved your engine.
If it's not seized, well the question is why the coupler let go.

I had this exact problem last June (coupler let go without anything seized).

The coupler had about 15K km on it and was on the car since 2014.

Like Stan said, you can only change the coupler and go on.
Or put a new Laso pump. That's what I did as I didn't want the coupler to let go again without any good reason like a seized impeller/bearing like it should.

Also, did it start to over heat soon after a fast RPM change like passing a car?

If so, go strait to the coupler.

Good luck.

Imo000

When you are testing the thermostat outside the engine, make sure to test it a few times and see if it opens consistently all the way all the time. I had one that opened perfectly the first time and a little less the second time and barely the thirst time.

byrdman454

I emailed with Ed about this and his Guardian WP. He suggested another method for determining whether or not it is the thermostat or WP without draining the coolant and removing the thermostat. This sounds like an easy test.

Here is his suggestion: The bypass hose going to the expansion tank will show flow even with a bad thermostat. It’s the hose that comes from the water bridge between the front cylinder heads which the water neck is attached . It will flow hot or cold. It circulates water through the system as the engine heats up. It also helps “burp” the system of air. If the fluid level is low enough you should be able to see it if you open the cap on the tank when it’s cold and de-pressurized. As long as there is fluid in the system it will pump out water as long as the pump is pumping.

byrdman454

I will try this after work today and report back this afternoon.

Mrmerlin

that sounds like a valid way to test the WP flowing,
I am betting a water pump issue

byrdman454

No flow, so WP is not pumping. I cancelled my order for the thermostat. I will now pull the TB and see what is going on with the Guardian. I will need to decide if I should have the Guardian checked/rebuilt or go with a Laso. Hopefully there is some obvious dragging/issue with the Guardian bearing which caused the coupler to shear. I will report back when I find something.

byrdman454

This Guardian has worked flawlessly on a daily driver for 5.5 years and 56000 miles so I am not upset with the quality of Ed's pump at all. I would really like to keep using it if it can be rebuilt.

Imo000

Can you turn the rubber coupler around?

byrdman454

I could, but something caused the coupler to shred the first time so it will happen again. I am hoping there is some dragging or issue with the bearing that caused this so I know what happened and can just get it rebuilt by Ed.

davek9

That's a GREAT tip and good suggestion for sure, thanks Ed and thanks for sharing

Dave K

Imo000

At nearly 60K mile, the teeth could just simple wore off too. I would have a good look at it when the covers are off.