macaroni 17 1 Cars Posted January 26, 2006 After fitting a new gearbox and my 4-2-1 manifold, my xs has developed another problem. I think I know what the answer is, but I would like a 2nd, 3rd or even 4th opinion... The engine gets very hot, but the heater is ice cold and the thermostat opening doesn't help. The radiator is hot, but the bottom hose is cool. The water in the expansion tank is also cold. I have flushed the rad and engine, so no obvious blockages, replaced the thermostat and checked the water pump. All seems OK. I guess it is either a head/gasket problem, but there is no emulsion in the oil, it doesn't lose water and I can't see why the heater wouldn't get hot. Anybody got any other suggestions before I whip the head off? Cheers, Antony Share this post Link to post Share on other sites
Jer309GTi 3 Posted January 26, 2006 Have you bled the air out of the coolant? Share this post Link to post Share on other sites
macaroni 17 1 Cars Posted January 26, 2006 I have had it running for about 10 minutes with the bleed screws open and nothing coming out but air. I had to turn if off because it was about to boil. Thing is I have done nothing with it to warrant air getting into the system. Share this post Link to post Share on other sites
macaroni 17 1 Cars Posted January 26, 2006 It was 2 days ago. It hasn't leaked and even if that was the problem, water should still circulate around the engine. All good suggestions, please keep them coming! Share this post Link to post Share on other sites
DaveW 6 Posted January 26, 2006 does the water pump work? Share this post Link to post Share on other sites
Alastairh 47 Posted January 26, 2006 I've had this in the past. Tu 8v engines are a pain to bleed, im currently running thermostat less... Alastair Share this post Link to post Share on other sites
DaveW 6 Posted January 27, 2006 yeah they are, you have to bleed them in a set way i think.... Share this post Link to post Share on other sites
macaroni 17 1 Cars Posted January 27, 2006 I removed the water pump last night and it is perfect. It does seem like an air lock as the heater is always cold, but I have bled it. Maybe I should bleed it some more. I removed the water pump last night and it is perfect. It does seem like an air lock as the heater is always cold, but I have bled it. Maybe I should bleed it some more. Thanks for the suggetions guys. Share this post Link to post Share on other sites
trogboy 17 Posted January 27, 2006 You say you've fitted a new gearbox? You haven't managed to switch the coolant temperature sensor wiring with that of the engine temperature sensor wiring have you? The connector on the coolant temp sensor on the thermostat housing should be red, If it is black then check the engine temperature sensor below the dizzy on the head as this connector should be black. If you have swapped the two then the engine will think it is overheating when in fact it isn't, as the head gets hotter then the coolant - hence making the temperature warning light come on when up to normal operating temperature. Failing that are you suspending the expansion bottle above the rest of the engine when you are bleeding the system? If you elevate it and add the coolant here you can open both bleed points and the radiator top cap then close then sequnetially as coolant reaches them. Make sure the engine isn't running though. Then run the engine until the radiator gets hot, stop it and bleed again. If the radiator gets hot then the thermostat is opening and the bottom hose should be cool as otherwise the radiator wouldn't be doing it's job. Share this post Link to post Share on other sites
macaroni 17 1 Cars Posted January 28, 2006 The temp sensors are all fine. I refilled and bled the cooling system today and something strange happened... The bleed screws started to spew out water and the heater began to get hot and I thought that is had been cured, when all of a sudden, the bleed screws went dry and the heater went cold. The temp gauge just went sky high too. The top hose was cold, but the expansion tank was under pressure and would overflow if the top was removed. It seems like the system is sealed when the car is cold, but after a few minutes of running and getting warm, an internal leak appears and sends water, under pressure into the bottom hose of the radiator and out into the expansion tank. It points to a head gasket or cracked head to me. Lucky I have a spare, ported head to go on!! Share this post Link to post Share on other sites
macaroni 17 1 Cars Posted February 3, 2006 Well, it turns out to be a head gasket after all! There was a rusty split in it just outside of number 1 pot. Thanks for all your suggestions. I just have to decide what cam to have in the ported head now... Share this post Link to post Share on other sites
