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Jerry, Master Mechanic
Category: Car
Satisfied Customers: 17220
Experience:  ASE master, 30+ years. All makes and models. Trouble shooter, shop forman, service manager
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Sub: Abnormal Engine Overheat Conditions "Mornin Doc," Beyond

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Sub: Abnormal Engine Overheat Conditions
"Mornin Doc,"
Beyond a defective thermostat, what would cause a rebuilt engine to basically peg out on temp readings @ idle on a friend's PV especially engine shut down?

Okay, engine indication "normal" when driving, even when at 70 MPH and sustained for example, an hour. I drove the PV a little myself and it scoots very nicely and the engine hums.

- When the engine is turned off, the temp reading goes full peg to hot. Climbs from 1/4 heat immediately at shut down, climbs to off scale full hot almost immediately again when the engine is turned off? Had to raise the hood & let the engine cool off, took almost an hour (time till return to 1/4 heat indication on gage).
- Engine - B-1800 (same as my p1800)
- Compression, timing, dwell . . . fuel etc all good to go
- Less than ~ 300 miles on rebuilt engine!
- Oh yeah, the water pump. and a new (refurbished radiator) already replaced.

Hello and welcome, Super mechanic here. Thank you for trusting us with your concern. I will do my best to help you with your question.


Unfortunately, it sounds like you may have a blown head gasket and you’ll likely need to take it in to get it repaired or at least do the test yourself.


About your friend's vehicle.



The first thing that you want to do is check the cooling system for any exhaust gases. There is a tester for that, that you can gt from Autozone for about $20. It comes with instructions, but there is a blue fluid that is used in it, if the fluid turns yellow, that is exhaust gases.


Block tester available as:

Napa BK.(NNN) NNN-NNNN/span>


Part Number:

If there are any exhaust gases in the cooling system, that will cause more pressure than desired and will allow the engine to burn coolant and/or heat the coolant up too high. Most times not filling the crankcase with coolant either.

If there are, then there would be an internal engine problem, like a head gasket or head.

Of course, you will want to make sure that the system is full, the coolant is circulating,as well as the pressure cap holding pressure. Thanks

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