Severe overheating - any advice?

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Sepp
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Joined: Thu Apr 30, 2020 9:12 am
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Years Owned: 1974

Severe overheating - any advice?

Postby Sepp » Thu Apr 30, 2020 9:27 am

I have had my 1974 Toronado for 5 years now. Runs perfectly and is just a blessing and a candy. Some months ago, it started to overheat so badly, after only 15 minutes of driving it without AC, that it shut down. Cooling water was boiling. After letting it cool down, I was able to drive it home, with the heat on max. My mechanic diagnosed a leaky central gasket - so he changed that. Big bill (over $2k), plus all new spark plugs and hoses. They also fixed the cylinders. I went home happy - but at my first drive, the same overheating occurred. Strangely, the heat warning does not come on. It simply shuts down. I took it back, and the mechanic found a disconnected hose. Changed it and put in a new thermostat and a new cap on the radiator. I took it home and tried it - still the same, after maybe 15 minutes of driving, no AC, the cooling water boils and the motor shuts down. We had already put in a new water pump in 2018. Radiator is new. I am at the end of my wits. :(
I should add that it never cooled down good, particularly in stop-and go traffic, so I was never able to use the AC, at least not for long and only on the highway. I live in Florida, so that has been a problem even before this extreme overheating now. Any advice on what to do now would be greatly appreciated.

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Otto Skorzeny
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Years Owned: 1966 Toronado

Re: Severe overheating - any advice?

Postby Otto Skorzeny » Thu Apr 30, 2020 11:52 am

First off, I'd demand my $2000 back for the misdiagnosis and subsequent, possibly needless repair.

There are a million reasons why an engine overheats. Incorrect timing, dragging brakes (yes, I've seen that before), clogged radiator, clogged hoses, bad thermostat, rust and corrosion in the water jacket, bad water pump, poor air flow through the radiator, etc.

How many miles are on this engine? Since its been running too hot for a long time and the new water pump didn't do any good, I'd suspect you have a deeper problem like rust clogged water passages, blown head gasket(s) or cracked head(s).

Is the timing set correctly? Timing advance systems working properly? Perhaps jumped a tooth on the timing chain if its a high mileage car.

I'm not sure what you mean by "fixed the cylinders", or "leaky central gasket". What is a central gasket?

As for the overheating warning light not coming on, I'd bet the guy didn't hook up the temperature sending unit (maybe on purpose?).

The shut down is normal for an extremely overheated engine. Your car is getting very, very hot which is not a normal overheating problem from a leaky hose or radiator. You didn't say there was a visible leak but have you had to add coolant to the radiator? If so, you have a blown head gasket or cracked head. Any steam coming from the exhaust?

If all of the above checks out correctly - timing correct, no leaks, new radiator and t stat, etc, I'd have top say your water jacket is badly corroded and clogged.

You can try flushing with one of the caustic additives available but if it's as bad as it seems, you'll need to pop out the core plugs and get in there with a long stiff brush, picks, etc. You can get at other nooks and crannies with the heads and intake off.

Sepp
Posts: 2
Joined: Thu Apr 30, 2020 9:12 am
TOA Membership Number: 0
Years Owned: 1974

Re: Severe overheating - any advice?

Postby Sepp » Thu Apr 30, 2020 2:55 pm

Thanks for that! I am German, so not always using the right terms. What was changed was the main gasket. When opening up the motor, they found that some cylinders were cracked so they welded that and it basically got a valve job done, which, I assume, is a good thing. No leaks though - no steam or water coming out. Breaks are new. So this might be about some passages being clocked up or the timing you mentioned. About 80,000 miles on the engine now. Thanks!


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