Opel GT Forum banner

1 - 6 of 6 Posts

·
Opeler
Joined
·
99 Posts
Discussion Starter · #1 ·
Well...i got my GT back from the mechanic today. There is one problem though, about 20 or 25 minutes after i picked it up, it began to overheat. It wasnt suddenly, it just gradually creeped on up until I looked over and noticed that it was nearly in the red. So I pulled over to allow it time to cool down and then about half an hour later, i went on my way again. By the time i got to my house, which is about 5 or 6 miles from where i left it, it was almost in the red again. While at the shop, the head was removed and the water jacket cleaned out, however i dont know if the radiator was flushed again...so im hoping thats the problem....while the head was off, it was sent to the machine shop and boiled(?) so that its cooling system would be as free flowing as possible. Anyhow, I guess maybe tell me if my theory is sound...
Thanks,
Rob
 

·
U-2 Driver
Joined
·
126 Posts
Do you have the fan shroud installed? Sounds petty, but ended up being a big deal down south with my GT. Make sure that the gaps are sealed thus increasing the efficiency.
 

·
Registered
Joined
·
6,344 Posts
It may sound a bit funny but did the mechanic put a thermostat back in the head and if so what temp range was put in? Also do you have a stock 2-row radiator or a newer 3-row installed? Next question, what shape is the lower radiator hose in? I gave a long post awhile back on thermostats and their function that shows what can happen if the wrong temp range or if the thermostat is left out. And I have seen a lower radiator hose collapse from the suction of the water pump at medium range RPM. Any one of these could cause your symptoms along with a partially clogged radiator. A lot of things to consider and eliminate as possibilities for your heating problem.
 

·
Old Opeler
Joined
·
5,564 Posts
What was Done?

Depending upon what was done to your motor by the mechanic - the head was off and the block worked on too by the sound of it.

Check that both the Valve Timing (ie camshaft phasing) and the iginition timing is correct and not retarded or advanced too far. If the head and/or block were surfaced then the camshft will be out of the correct valve timing position unless the cam drive wheel has been moved a bit to compensate.
The ignition distributor is directly driven from the crankshaft snout so cam timing does not affect ignition timing (unlike most motors which drive the distributor from the camshaft) but both the ignition timing and the advance/retard mechanisim in the distributor need to be checked for correct settings.

Overheating "kills" Opel cylinder heads because they crack when overheated.

Check the thread about the two extra cooling holes that can be made in the headgasket too - they cool the most heat stressed area of the cylnder head - between the centre exhaust ports. The thread is "Improved Coolant Flow to cyl 2 & 3 exhaust valves." "Head Gasket" in the search box turns it up along with several other interesting threads.
 

·
Opeler
Joined
·
99 Posts
Discussion Starter · #5 ·
Oh, sorry, yeah the fan shroud is installed, and when the head was off, we found that the water jacket ports from the water pump were completely clogged up so they were drilled back out. I think that the valve seats were redone and thats about all that was done to the head...most of the work was done replacing seals and such. On the block, all that was done was the waterjacket stuff.
....The thermostat is out but i think when it was in, it was a 180, which has no bearing now...i didnt check the lower radiator hose.
Thanks so far,
Rob
 

·
Registered
Joined
·
6,344 Posts
Well Rob, I guess you didn't read my previous post on thermostats. With a partially clogged cooling system, which it appears you have/had, and no thermostat, you are susceptible to overheating. Without a thermostat in the system to restrict the flow, the coolant does not stay in the radiator long enough to be cooled down. The slowly rising temp is a dead giveaway of that. I would suggest you use a chemical flush of the entire cooling system, possibly twice following the instructions on the container. If you had to clean out the passages in the block that you could see, there are many more that you couldn't see that could be plugged also.
 
1 - 6 of 6 Posts
Top