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cooling issues probable headgasket (among other things)


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sit down, get a bru and find your reading glasses,

ok, my car is a mk2 with a obd 1 2.8 and it seems to have no power top end (between 4-6k) unless its cold, sometimes it will suddenly kick back in and regain power at normal temp but not very often... ..and not for long. after a little un educated inspection i have realised the following....

1. there is no coolant running through the pipes to the throttle body pipes.

2. the return from the heater matrix is cool.

3. when revved up with the expansion tank lid off you let off and lots of large bubbles come through the water (i smelt it and i doesnt really smell like exhaust gas but when tested with the the block tester after a few pumps it turned a greeny colour)

4. it over heats when stood still but not when driving (no matter how hard its driven)

5. if lid is on expansion tank and the car runs to operating temp then the lid is removed it pisses all the coolant out the top.

6 there is no steam from exhaust

7 there is no oil in the water or vice versa

8 i cant seem to see an auxillary water pump anywhere

so what im asking in this big essay is do you think its the gasket or a broken water pump which wont circulate or a bit of both. do you think the power loss problem is related or maybe a dodgy wire, does anyone have a diagram for cooling pipes? and wtf should i do next!!! any help or guidence would be much appreciated! cheers guys.

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1. there is no coolant running through the pipes to the throttle body pipes.

- If they are the ones I think you mean they are vacuum lines not coolant!

2. the return from the heater matrix is cool.

- Is the heater matrix free flowing? Does hot air come out of the heaters? If the blowers blow hot air that heat is coming from the coolant so the return pipe will be cooler (though still pretty warm)

3. when revved up with the expansion tank lid off you let off and lots of large bubbles come through the water (i smelt it and i doesnt really smell like exhaust gas but when tested with the the block tester after a few pumps it turned a greeny colour)

- If you've let water come out as you suggest in #5 then when it cooled it will have sucked air in.

4. it over heats when stood still but not when driving (no matter how hard its driven)

- Did the cooling fans come on? If not check the temperature switch in the radiator (common fault)

5. if lid is on expansion tank and the car runs to operating temp then the lid is removed it pisses all the coolant out the top.

- Normal :) Things expand when they get hot - including your coolant. The coolant system pressurises when hot - when you take the cap off the pressure equalises with atmospheric pressure so it pisses out all the expansion fluid.

6 there is no steam from exhaust

7 there is no oil in the water or vice versa

- Good signs that the head gasket is fine...

8 i cant seem to see an auxillary water pump anywhere

- As above - it's a coke can size cylinder with small wiring connections in the top to the right of the engine near the main wiring harness connection.

Plugging a vagcom reader up to it is likely the fastest way to find out why the power comes and goes... sounds like a faulty sensor - air intake temp maybe?

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firstly thanks for the replies, i will check behind the coilpack for the aux water pump.

1. there is no coolant running through the pipes to the throttle body pipes.

- If they are the ones I think you mean they are vacuum lines not coolant!

1-if they are vacuum why are they tapped off the coolant pipes? its the two black pipes which go into the top of the throttle body.

2. the return from the heater matrix is cool.

- Is the heater matrix free flowing? Does hot air come out of the heaters? If the blowers blow hot air that heat is coming from the coolant so the return pipe will be cooler (though still pretty warm)

2-yes the blowers are now blowing hot air but were not before?? i went out tonight and the air started coming through warm.

3. when revved up with the expansion tank lid off you let off and lots of large bubbles come through the water (i smelt it and i doesnt really smell like exhaust gas but when tested with the the block tester after a few pumps it turned a greeny colour)

- If you've let water come out as you suggest in #5 then when it cooled it will have sucked air in.

3- yes exactly what i thought but as the bubbles were coming out i was topping the colant back up and the bubbles just kept coming!!

4. it over heats when stood still but not when driving (no matter how hard its driven)

- Did the cooling fans come on? If not check the temperature switch in the radiator (common fault)

4-yes the fans came on but as if they were on a slow setting where abouts is the temperature switch on the radiator? can i test it?

5. if lid is on expansion tank and the car runs to operating temp then the lid is removed it pisses all the coolant out the top.

- Normal Things expand when they get hot - including your coolant. The coolant system pressurises when hot - when you take the cap off the pressure equalises with atmospheric pressure so it pisses out all the expansion fluid.

- ha ha believe it or not i went to physics allthough it doesnt sound like it! yes i understand that but i mean most of the coolant does come out and i am a mechanic and i have never come across a car that does this before.

6 there is no steam from exhaust

7 there is no oil in the water or vice versa

- Good signs that the head gasket is fine...

7-i know im sat here fingers crossed

8 i cant seem to see an auxillary water pump anywhere

- As above - it's a coke can size cylinder with small wiring connections in the top to the right of the engine near the main wiring harness connection.

8-cool il look for that

Plugging a vagcom reader up to it is likely the fastest way to find out why the power comes and goes... sounds like a faulty sensor - air intake temp maybe?

i dont have a obd port or if i do i cant find it! upon closer inspection the throttle position sensor has a dodgy plug soldered onto it can someone tell me which colour wires goes to which of the three wires on the plug once again thanks very much!!

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firstly thanks for the replies' date=' i will check behind the coilpack for the aux water pump.

1. there is no coolant running through the pipes to the throttle body pipes.

These are coolant pipes, sounds like an airlock

2. the return from the heater matrix is cool.

2-yes the blowers are now blowing hot air but were not before?? i went out tonight and the air started coming through warm.

same as above, would be caused by air lock

3. when revved up with the expansion tank lid off you let off and lots of large bubbles come through the water (i smelt it and i doesnt really smell like exhaust gas but when tested with the the block tester after a few pumps it turned a greeny colour)

Does greeny colour = exhaust gases ???? You wont be able to smell it

3- yes exactly what i thought but as the bubbles were coming out i was topping the colant back up and the bubbles just kept coming!!

Carry on going, all the air hasnt come out

4. it over heats when stood still but not when driving (no matter how hard its driven)

- Did the cooling fans come on? If not check the temperature switch in the radiator (common fault)

Above most probable fault

5. if lid is on expansion tank and the car runs to operating temp then the lid is removed it pisses all the coolant out the top.

- Normal Things expand when they get hot - including your coolant. The coolant system pressurises when hot - when you take the cap off the pressure equalises with atmospheric pressure so it pisses out all the expansion fluid.

- ha ha believe it or not i went to physics allthough it doesnt sound like it! yes i understand that but i mean most of the coolant does come out and i am a mechanic and i have never come across a car that does this before.

As above this is normal for some coolant to come out, but not normaly all the coolant, if the headgauskit has gone between cylinder and coolant then the coolant system will be pressured by exhaust gases and all coolant can be expelled

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Next time you go for a drive when hot after a good run pop the bonnit and check if to see if your coolant hoses are rock hard, Change the rad temp fan switch anyway as there only £14 iirc from GFS

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