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Showing results for tags 'cylinder head'.
Just thought I'd share my experiences. I've just put a GT6 mk2 back on the road. It's running on a late Mk3 engine. Despite idling happily without overheating as soon as I drove it, the temperature gauge started rising in to the red. The engine was flushed with all sorts (including Fernox) but vey little crud came out from flushing and the drain at the rear of the block refused to do anything but dribble slightly (despite, bits of wire wiggling etc). The heater was lukewarm at best (although did help a bit to cool the engine if on full with the fan blowing). In the end bit the bullet, took off the cylinder head and after protecting cylinders etc with cloths, had a good go at cleaning out the rear of the block. Not surprisingly full of crud and scale. It didn't take too long and had it cleared out and running clear with water. The head was also pretty gummed up so treated that to a flush with phosphoric acid (40% strength bought off ebay). This latter substance is somewhat controversial - John D swears it wont work (only read his posts after buying it on someone else's recommendation). Anyway, it fizzed away for a few days and cleaned up things a treat. As the head was off I was sure I could rinse it out thoroughly so decided to risk it. Cleaned up the head, lapped the valves, got a new gasket and put it all back together. Far more hassle changing a diff. All working well, engine now not overheating, rear drain working perfectly. Heater is proper hot (not necessary I gather in a GT6 but nice to see it can work as expected). Moral of (my) story. Bite the bullet, don't arse about flushing and re flushing. Don't replace all manner of items (bought a very nice aluminium rad which I'm sure I don't need but then it does reduce a bit of weight up front!), water pump etc. Chances are your overheating issue is a cruddy block (especially if the drain doesn't work) and you may as well have a go at sorting it. Bob