Hello,
I have purchased a 1981 300SD that strats from the first cranck, and only emit little white smoke. the car runs fine for 2-3 miles and then strats to emit white thick smoke. I have flushed the radiator and noticed that the water pump is not pumping any water rather the water just flows out of it without any pressure.
could the problem be in the water pump?

thanks for your help

Welcome to the forum.

Two questions:

1) Does the smoke have a sweet smell, like anti-freeze, or is it just raw diesel fuel?

2) Does the vehicle use coolant? Can you notice a drop in the expansion tank after several hundred miles?

Hi Brian,
It does smell like raw diesel burning not anti-freeze.
before I flush the radiator the car had anti-freeze and the burning didn't smell like antifreeze burning. now I'm using only water for coolant. expansion tank loses coolant because the car heats up to the extent the coolant would be boiling in the expansion tank.

thanks

make sure your pressure cap is good and fill to the cold water mark in the expansion tank. If it drops below this your engine is losing coolant, probably through a failed head gasket.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Raw diesel fuel, unburnt, will give the white smoke that you are seeing. But, I would expect it at all times, and not just when the vehicle warms up fully. However, it might be a good idea to pull the injectors and have them tested. See the sticky regarding "tools for rent" on the first page. There is a fellow who will test them for you at a very reasonable cost.

But, I'm concerned about your statement that the expansion tank loses coolant because the car heats up. A properly functioning cooling system, with a 50/50 mix of anti-freeze, and a suitable pressure cap won't boil any coolant at any time. If this is not the case, it needs to be addressed.

It's entirely possible that the white smoke is caused by a coolant leak into the combustion chambers. This would be a severe situation that needs immediate attention. The cylinder head would need to be removed.

Thanks,
How to test a failing water pump?

Normally they fail because the bearing fails and coolant pours out the weep hole. If this is not occurring, it's possible (although rare) that the impeller is corroded due to negligence in maintaining the coooling system.

Remove the pump and check out the impeller. Look for corrosion and or pieces missing on the blades. Note that it's not very common.

I'm sorry, I didn't fully describe the problem.
after the car starts smoking thick white smoke, if I stop at any traffic light the car would stop running and will not restart for 15-20 mintues, after that time has passed the car will start normal start

I would let it idle from cold noting coolant level. Coolant level should rise somewhat as it gets warm and stay there. Coolant temp should rise to 80-90C and stay there. If it doesn't, you should stop driving it. If you have a head gasket leak so big that it's quenching the cylinders and you continue to drive it that way, you can hydro-lock a piston. A stitch in time saves nine.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.