Engine overheat

[Al Squillante]

When it rains it pours.

I finally finished installing my refurbished fuel tank . Added new vent lines and finally was able to start the engine. After adjusting the carb I got the engine running great. I want to retorque the head and check the valve clearances. I just completed installing the head after rebuild. However after running the engine for about 30 minutes it started to boil over. I checked the thermostat before I installed it and it was ok. I dont know where to start. Should I flush out the cooling system, pull the radiator , or pull the water pump or all of the above. The car was laid up in the garage for 15 yrs. I also see that I have a oil leak at the back of the engine which muight be the rear engine seal.

Any help would be appreciated

Al S

[2ManyZs]

Since it sat for so long, I would start with the radiator. Take it out and have it cleaned and pressure tested, it might not even be salvageable, but a good radiator shop sould be able to re-core it if necessary. Sediment, rust, corrosion are usually the first thing to worry about if the car has sat for that lenght of time. You can get new replacement radiators for as little as 150 or so for a stock 2 row core radiator up to a 4 row core for a little over 300, ust to give an idea of how much to spend on the old one before you give up and buy a new one.

Personally, I usually go with either a 3 or 4 row since the Z's have a tendancy to run a bit hot anyways, costs a bit, but it's better and cheaper than warping a head.

You say you checked the thermostat, but since they are so cheap, I'd just go a head and replace it and have a little extra piece of mind.

After you repair/replace the radiator I would suggest a good flush of the entire cooling system as an added precaution, some of the same corrosion and sediment that ruin a radiator can alco block water passages in the block.

[Bambikiller240]

Originally posted by Al Squillante

..... I just completed installing the head after rebuild. However after running the engine for about 30 minutes it started to boil over. I checked the thermostat before I installed it and it was ok. I dont know where to start. Should I flush out the cooling system, pull the radiator , or pull the water pump or all of the above. The car was laid up in the garage for 15 yrs. ..................

Hi Al;

Since the car was laid up for 15 years, I would replace the water pump if you haven't replaced it yet, AND I'd have the radiator cleaned (rodded out) and pressure tested. It will be money well spent in ensuring that your Z is a reliable, cool running car for a long time to come.

Good Luck!

[Daniel]

The thermo would have to open to refill the block that was drained when the head was removed.Adding more coolant would be my first thought(50/50 mix) .Is the coolant all new?How did you check the thermostat?

[tanny]

After 20 years of storage my z had quite a bit of a soft, wax like sediment built up, clogging the inlet to the thermostat housing and water pump was severely corroded. Would definitely have overheated if I hadn't first flushed the radiator and block and replaced the thermostat, all rubber hoses, and water pump. All suggestions above are necessary for a car stored that long. Good luck, Victor.

[Al Squillante]

I pulled out the thermostat and retested it. Seems to work OK.

It opens up at a little under 180 F. I ran the car with the thermostat out and no pressure cap. After about 25 minutes the water in the radiator reached about 200 degrees and I shut down the engine but it was mount Vesuvious again. The pump seems to be wooking . I can see flow in the top of the radiator. If I touch the radiator it is hot on the drivers side and coll on the discharge side of the of the radiator. I think I will pul the radiator and have it checked and if NG will replace it. I probably will replace the pump. I know if I put the pressure cap on it willl raise the boiling point up by 30 + degrees but still dont think all is OK.

Thanks for the response

Al S

[ZmeFly]

your t stat seems to work operative word seems, and so does your waterpump, both are very inexpensive and cheap insurance against damaging that head you just put some good money into.

not only that both parts are easy to r and r.

be safe instead of cheap and replace those old parts. its just good sense and even better insurance.

not trying to pine on that but like the others said its just the right thing to do