1.6TD over heating

[Nick M.]

Hoping someone can help me with an over heating issue. I'm a diesel noob so bear with me. I have a 91' Ecodiesel that I've been working on over the last year or so. I'm getting to the home stretch of having it road ready but can't sort out the over heating.

Warms up quickly, after I hit the road the temps climb fast and within 3 minutes the light comes on. The upper rad hose gets very hot and has a lot of pressure built up. I replaced the thermostat and still nothing.

[Mark(The Miser)UK]

From cold, crank start and run for 10 seconds. Stop and check for pressure build up. If significant then it will be your head gasket.  Do you get continuous bubbles in the little return stream to the header tank? That's another sign of h/g leak.

[Nick M.]

No significant pressure after 10 seconds. Really only pressurizes after a short drive.

[Nick M.]

Ok, replaced the thermoswitch. The fans only run when the hvac is on, wont turn on own their own. Ran the car for about 5 minutes, upper hose started to get pressurized around 3.5-4 min in (the temp gauge was around 3/4). Lower hose felt like cool water.

[Mark(The Miser)UK]

Do you get a nice spout of water into the coolant vessel , even at idle?

[Vincent Waldon]

If its not a simple blown headgasket my other interweb guess (based on recent personal experience ) would be that you could be starting to develop one or more small cracks in the head... usually radiating out from the pre-chamber cutout.

My experience was that the car passed the 10-second pressurization test perfectly, started and ran fine, good compression across the board, but after driving for 5-10 minutes experienced pressurization of the coolant system, higher temperatures,  and some coolant consumption.  Removing the head revealed a normal headgasket but small cracks radiating out from two pre-chambers.   Replacing the head fixed the issue permanently.  I didn't waste any money pressure-testing the old head  

My theory is that when the cracks are small they stay sealed, more or less, until the engine is good and hot.  I never did a full-hot compression test, but given the size of the cracks I don't know if I would have been able to detect them anyways.

Exploring this possibility... are you seeing any coolant consumption on longer drives?

[Nick M.]

Do you get a nice spout of water into the coolant vessel , even at idle?

Not at home right now so I can't start it up and check, but I don't believe I was.

Just recently got it running. Haven't driven it more than 2 miles, as soon as the coolant light came on I brought it home.

Exploring this possibility... are you seeing any coolant consumption on longer drives?

Just recently got it running. I've only driven it about 2 miles or so, as soon as the collant light came on I brought it home. No noticable consumption there though.

[arnold]

If the lower hose is still cold after a drive and your thermostat is fine (a new one dousn't mean it works so check it just to be sure) i'm pretty sure your waterpump has stopped working,they don't fail often but when they do its with the exact same sympthoms