coolant airlock?

[jayc]

Hi, help needed. Ive just fitted a replacement 1z tdi engine into my bus and im struggling to get the rad warm.
A few goes at bleeding the system failed so I decided to remove and inspect the rad. I found this blocked so I fitted a new one. further goes at bleeding failed once again, thermostat checked and found stuck closed when hot. system is not pressurising and ive had the rad warm once when revviing the breasticles off it whilst bleeding but then turns cold on idle and when driving. Im now about to inspect the water pump although it does seem to flow. the waterpump, thermostat and housing were off my old engine and were working fine previously. Any ideas on something obvious im doing wrong? Running out of time now for the oktoberfest!
Jay..

[dugcati]

The basic idea is to get the front of the van as high as possible - on a sloped drive up on ramps at the front is how I did mine....

Bear in mind that you'll need to drive the van a little before bleeding as the thermostat wont open/will take for ever if you let it sit idling on the drive from cold when your bleeding the rad remember to keep the header tank full and the pressure tank full also. Also when bleeding I found that I could use a spanner to crack the bleed nipple with one hand and reach under the van and grab the throttle cable as revving the engine increases the water pressure

[Oldiebut goodie]

This has come up several times before - some replacement engines have been found to use water pumps that rotate in the opposite direction resulting in that you don't have a water flow when you use your old pump and direction of rotation.
Worth checking to see. (you may just need a longer or shorter belt so that the pump rotates in the opposite direction - the vanes will tell you which way the pump should run if there is no discernible arrow on the body)

[colinMSC]

This has come up several times before - some replacement engines have been found to use water pumps that rotate in the opposite direction resulting in that you don't have a water flow when you use your old pump and direction of rotation.
Worth checking to see. (you may just need a longer or shorter belt so that the pump rotates in the opposite direction - the vanes will tell you which way the pump should run if there is no discernible arrow on the body)

is this true I thought all vw water pumps rotated clockwise

[Oldiebut goodie]

Take a look at this thread. This spells out the difference.

[colinMSC]

that's what i like about this forum , there is always some one that will help , i read this post because a friend is having the same problems with his aaz ever since he fitted it , now i know what is wrong thanks for the info .

[jayc]

Removed waterpump housing, removed and checked waterpump..all ok and impeller as new. As i'd purchased a new waterpump just in case, this was then fitted(it was nice and shiney!). Bled and tested, temp still rising and full of air. Once again thermostat was removed and this time left out. Bled and tested in about 10 mins.. low and behold temp rises perfectly! no air and fan cuts in on time. What the hell is going on here?

[Mickyfin]

Sounds like a faulty thermostat?

[billy739]

replace with a good quality stat , try a brickwerks one , try to avoid gsf!

make sure your expansion tank cap is good and not leaking as it will stop you bleeding the system .