blowing cold air

Hi lads ,i have a diesel p38 my car is only blowing cold air,have taken blend motors out and try,d the temperture but to no avail,all the motor seem to do is open flaps,so i have done this manually open and closed but cant seem to get any heat,also iam getting water blowing back in the expansion tank any idea,s about that could there be an airlock somewhere,cheers pat

If you have manually opened the Blend Flaps to Hot...and it is still cold I can only summise either you have an air lock or someone has bypassed the heater matrix due to the O rings leaking!

The heater matrix should always be hot, it is part of the bypass circuit and coolant is circulated from head through it and back to head to aid warm up before main thermostat opens to release coolant to radiator. At which time the bypass valve closes for normal operation.

wammers said:

The heater matrix should always be hot, it is part of the bypass circuit and coolant is circulated from head through it and back to head to aid warm up before main thermostat opens to release coolant to radiator. At which time the bypass valve closes for normal operation.

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Are you telling me or the OP Tony???

Saint.V8 said:

Are you telling me or the OP Tony???

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Sorry Ant the OP.

wammers said:

Sorry Ant the OP.

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Ahhh.....I see

Would an airlock cause the pressure in the exp as nsion tank,i dont think there is a leak in the matrix as the footwell is dry

paddocks67 said:

Would an airlock cause the pressure in the exp as nsion tank,i dont think there is a leak in the matrix as the footwell is dry

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Pretty unusual to have an airlock in there. As i said, it's part of the warm up circuit. Unless it's blocked. The water pump, pumps water from the front of the head through the matrix and returns to the rear of the head when the thermostat is shut and the bypass valve is open. When the thermostat opens the bypass is closed so coolant then goes through the rad. Either way the heater matrix should get hot long before the main rad does. Have a feel of the heater pipes and see if one is a lot cooler than the other as the car warms up. Coolant is fed from the header tank to one of the heater pipes so the matrix should be the one of the first things to be filled up.

paddocks67 said:

Would an airlock cause the pressure in the exp as nsion tank,i dont think there is a leak in the matrix as the footwell is dry

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The footwell may be dry because a previous owner *may* have bypassed it to stop it leaking!

Get under the dash and put your hand on the matrix and/or pipes leading thereto and see if they are warm....

Saint.V8 said:

The footwell may be dry because a previous owner *may* have bypassed it to stop it leaking!

Get under the dash and put your hand on the matrix and/or pipes leading thereto and see if they are warm....

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Pipes in the engine bay will do Ant. If one is hot and the other cold or significantly cooler after a couple of minutes of running, he has a problem.

wammers said:

Pipes in the engine bay will do Ant. If one is hot and the other cold or significantly cooler after a couple of minutes of running, he has a problem.

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Suppose that simpler....

Saint.V8 said:

Suppose that simpler....

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Indeed it is. Why get out of your chair and go out to see if it's cold, when you can send the wife out instead.

wammers said:

Indeed it is. Why get out of your chair and go out to see if it's cold, when you can send the wife out instead.

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:hysterically_laughi:hysterically_laughi

Yes wammers the hose coming from the cylinder head going into the bulkhead is warm,the one coming out isn,t what problem do i have,and what about the water blowing out of the expansion tank,what is causing that,

paddocks67 said:

Yes wammers the hose coming from the cylinder head going into the bulkhead is warm,the one coming out isn,t what problem do i have,and what about the water blowing out of the expansion tank,what is causing that,

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Either the heater matrix is blocked or there is an airlock which can also cause water to blow out of the expansion tank.

What is the best way to check for a blockage,and what is the best way get rid of an airlock

paddocks67 said:

What is the best way to check for a blockage,and what is the best way get rid of an airlock

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Remove the two pipes from the tubes that go through the bulkhead. Put a rag wrapped around an airline nozzle in the one that goes to the back of the head. That is reverse of flow. Gently and i really mean gently pressurise the matrix. NOT full pressure or flow at any time. Just a little squirt of air now and again. See if you get anything out of the other pipe. If you get coolant and then a free flow of air the matrix should be ok. Nothing or very little the matrix is blocked. As i said unusual to get an air lock in the heater matrix as it is in the warm up flow circuit. Coolant needs to go through the matrix to complete the warm up circuit.

I hate this ####in car

Now the radiator hoses are pressurising,surely not gasket,causing all this

paddocks67 said:

Now the radiator hoses are pressurising,surely not gasket,causing all this

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If you are not getting flow through the heater matrix and there is no blockage and it is now getting warm. I think i may be taking a look at the water pump.