Mrmerlin

I am with Seans diagnosis here. and its good opportunity to replace the thermostat seals and T stat and heater control valve and short hose and coolant cap.
might not be a bad idea to replace the waterpump with a new Laso with plastic impeller.
Or carry an extra shear bushing for the guardian and all the tool to swap it on the road.
NOTE dont run the car till the waterpump has been removed and inspected,
or you could damage the HGs

Bertrand Daoust

Thanks Stan.

Your advices are always very appreciated.

I'll do a pressure test and coolant test tonight.

And dig to the water pump after that and see what happened.

I have a spare Laso WP available. Thanks Luc!

Thanks again.

Bertrand Daoust

I put a pressure tester on the reservoir (14 psi).

It wasn't holding the pressure. Then noticed that both upper and lower hoses were leaking at the thermostat side. I tight both and it's good now.

I put back 14 psi and maybe lost 1/10 of a psi in about 15 minutes.
I think that's good. Right?

What I'll do next, is lift the car, remove the belly pan, air tube, air filter box and inspect every coolant rubber hoses, pipes, etc. with pressure applied and make sure that everything is tight enough.

I could not get some fluid today for the block tester. Might get some later this week.
Then I'll get down to the pump to look at it.

Thanks guys.

Shawn Stanford

Trinity says good luck with your repairs!

Bertrand Daoust

Say thanks!

worf928

The coolant, in liquid and vapor form, would have escaped from the vent tube of the overflow tank once the pressure in the system exceeded the relief pressure of the tank's cap. A new cap would release at no more than 14 PSI. An old cap might release at 7 PSI or less.

In either case you'd not, likely, find evidence of coolant: it would have vaporized if not vapor already and/or dripped onto the road while driving.

Already expressed possibilities: thermostat, guardian pump's bushing are spot on.

I think it highly unlikely that a head gasket popped. Your pressure test seems to confirm that (at least with a cold engine.) Leave the pressure on overnight, then pull the plugs and check for coolant in the cylinders. (I doubt you'll find any.) A super-clean plug unlike any of the others might, however, be a smoking gun.

worf928

If indeed that turns out to be the case, I'll bet Ed will be very interested in diagnosing the cause.

FredR

Bertrand,

You said that you had a temperature alarm flash up but unless I missed it, you did not mention where the temperature gauge needle was. Did it show abnormal behaviour in terms of higher indicated temperatures such as the needle moving into the red zone or clearly above where it normally sits?

Bertrand Daoust

The needle went right to the red zone.

The warning "Overheating" was flashing in red and little red light was on.

Not fun at all!

Before that happened, the normal driving temperature was right before the last white line (90C?) with a 83 thermostat installed last year. Before that I had a 75 degree thermostat and the normal temp. was just above the first white line. I didn't like that so put a 83 degree.

Thanks.

Bertrand Daoust

I'll leave the pressure tester on and see.
I'll check the plugs also. They're new from this year.

Thanks Dave.
BTW, nice meeting you in Chestertown!

FredR

Bertrand,

That clearly rules out a false indication.

Your symptoms appear very much like what happened first time my water pump lost the impeller during our hot summer time. Quite possible you puked some coolant from the expansion tank as the over pressure device in the cap lifted - is the cap newish or old?

That you are holding test pressure suggests the pump is the problem- will do no harm to take a look at the thermostat though given you will need to drain off the coolant to get at the pump.

I know just about squat about that type of pump but if the coupling has sheared in the way it is designed to do as a protective measure, it will be interesting to know why it let go. First things first however and probably time to extract the pump to see if that is the root cause of the overheating.

Bertrand Daoust

Thanks Fred.

hacker-pschorr

You don't really need to drain any coolant to get at the t-stat.

When I bought my 79 it had t-stat issues. I jacked up the nose as high as I could, coolant loss was very minimal since the t-stat housing was now the highest point in the system.

linderpat

I am going to remain very optimistic on this one. That car is too nice, too well loved to have some sort of major catastrophic failure.

Adk46

I'm planning to park on a hill and do just this in order to roughen up the powder-coating on the right-side nipple. It's so smooth that the hose works itself off, even with two clamps on it. I should remove the powder coating altogether; if the bridge comes out easily, I might. Stan suggested I should roughen up the inside of the hose, too.

When it does, the symptoms are rising temperature and then a low-coolant warning. The hose doesn't entirely pop off, it just starts leaking coolant - not a lot, but enough to relieve pressure. Some or most of the missing two quarts might be from steam. Nothing visible from inside the car, surprisingly.