3/4 temperature and no fan...

[jtanguay]

hmm yea those problems suck.  at idle my temp is perfect.   the fan even comes on!  but when i'm driving down the highway the temp gauge will creep right up and fan does not kick in (so the hot coolant is not getting to the rad...)

That's a classic symptom of a slipping impeller.  At lower rpms it's likely moving enough coolant that your fan comes on.  At higher rpms it slips enough that it stops moving coolant, the fan doesn't come on because the coolant in the rad is below your sensor temperature.  We had a few Cummins engines at work with this problem right from the factory.

right from the factory??? damn... I was hoping this wouldn't be my problem, but if it is i'd rather know about it.  so now, the water pump is slipping, can i not just spray the belt with some belt dressing and see if that fixes it temporarily? if it does then all I need is a new belt???  I do have a new belt to throw on...  or is it something internally that is slipping??

[aidan]

Jtanguay - they are DI pumps, didn't notice at first but only the first one is from a turbo DI. They are 3 litre engines I think, 11mm pumps if they are the same as before.


I'm leaving the expansion cap quite loose so the pressure can escape, have done for around 100 miles or so so i'm thinking air would have cleared now? Especially as i'm adding around 1litre a day back thats lost through steam and spillages

[jtanguay]

DI pumps for that little cash? damn! good price.  I'm thinking that my water pump pulley is slipping at high rpm.  3k rpm on the highway is cruising at around 100km/h because my gearing sucks.

[jtanguay]

oh yea aidan have you tried running a chemical flush through the rad system? I have done that, and it seems to have helped.  i have no problems getting heat through the vents  VERY hot air comes through when my temp is climbing.  enough to burn my hand or cook meat like a convection oven!  :lol:

if you're not getting hot air coming through your vents, then get your car to operating temp and feel the coolant lines going to the heater core, if they are both lukewarm then its plugged.  if its hot then its probably a problem with the vent doors.

[clbanman]

right from the factory??? damn... I was hoping this wouldn't be my problem, but if it is i'd rather know about it.  so now, the water pump is slipping, can i not just spray the belt with some belt dressing and see if that fixes it temporarily? if it does then all I need is a new belt???  I do have a new belt to throw on...  or is it something internally that is slipping??

Actually where we were having the problem was internally, not the belt on the pulley.  The impeller blade just went over the pump shaft, and the end of the shaft was then peened to hold the blade.  Once we took the pumps off, you could hold the pulley, and turn the impeller without turning the shaft.  The pulley was working fine, and a lower rpms the friction was enough to create some flow, but once the rpms went up and the impeller started to slip it was game over.

[jtanguay]

right from the factory??? damn... I was hoping this wouldn't be my problem, but if it is i'd rather know about it.  so now, the water pump is slipping, can i not just spray the belt with some belt dressing and see if that fixes it temporarily? if it does then all I need is a new belt???  I do have a new belt to throw on...  or is it something internally that is slipping??

Actually where we were having the problem was internally, not the belt on the pulley.  The impeller blade just went over the pump shaft, and the end of the shaft was then peened to hold the blade.  Once we took the pumps off, you could hold the pulley, and turn the impeller without turning the shaft.  The pulley was working fine, and a lower rpms the friction was enough to create some flow, but once the rpms went up and the impeller started to slip it was game over.

is there many reported cases with vw's??? man I really don't want to change the WP...

http://parts.autopartsonlinecanada.com/parts/apocanada/quote.jsp?year=1991&product=G3000-170730&application=000610161&part=Water%20Pump&category=G

on that site its showing me 3 different style WP's... is going with the cheapest one okay??? or is the OEM one my best bet?

[burn_your_money]

I could be wrong but I think the ones from Canadian tire come with a lifetime warranty and are $50

[jtanguay]

lifetime warranty... i'm down for that !  

[Doug]

Before you panic to replace that pump, open the thermostat housing, removing the T stat. Now you can see the WP impeller. Hold the pulley and try to turn the impeller. This simple check should satisfy all your questions about the coolant pump impeller integrity. My experience has shown that the pump is not the problem. Overheating is caused by all sorts of issues but with the average age of the diesels getting older don't overlook simple things like the amount of wear in the engine. Typical problem areas are rings and valve guides supplying significant amounts of fuel in the guise of lubricating oil. Fuel equals heat. Solution is simple. Rebuild the engine.

[jtanguay]

but doug the issue is that my rad fan isn't even kicking on... it does kick on at idle though.  mainly because the hot coolant isn't even making it to the rad.  

i can only hope that there isn't permanent damage to the engine from this.  (i always make sure to drive carefully and limp home if the temps rise too high)

[burn_your_money]

your rad isn't clogged in any way?

[Doug]

JT, I went through the same thing as you. I carefully bled the system, changed T stat for an OEM, put a new reservoir cap on (system pressurising), checked WP for impeller slippage, installed a new alternator/WP belt, removed the rad and flushed with a garden hose, changed the lower rad hose and bypass piece, double checked timing belt pump/crank settings all to no avail. When I finally decided to do some engine work after a long journey that confirmed excessive oil consumption and also saw the engine temperatures get high considering that it was -25C (7litres/1500 Km), I was pleasantly surprised to find that the temperature guage seemed to settle down at a steady 5/8 position with little variation and the fan never seems to operate (maybe I should check the relay sensor in the rad?) The car does not get hot at idle to the point of needing the fan which it did before. Oil consumption has continued to improve as I assume that the rings are conforming to the slight out of concentricity of the bores (rings only replaced). The oil consumption is now below a litre/2000 Km. What do you think about my hypothesis?

[jtanguay]

well funny thing is... i flushed everything but the rad  :oops: because i flushed without the thermostat.

ever since i got the new thermostat the car has been overheating.  (only say 100C max which isn't so bad.. at that point i let off the pedal and watch it go down...)

my car will hold perfect temperature at idle.  that's what really gets me..  and my car doesn't burn oil either... mainly because its 5w50 synthetic oil.  well okay the past 2000km it probably lost about 1 litre, but I'm still working out some issues with the dipstick, as in maybe i put too much oil to begin with??  :roll:  :oops:

but if the rad was clogged, then at idle would the coolant still flow through it enough to kick on the thermoswitch and turn the fan on???  

I'm going to try the WP route... there's no telling when the PO changed it.. I'd even assume it's the original!  approx 386'000km...

Oh yea I also got rebuild injectors from smog that andy2 helped me install.  that seems to have lowered the temperature as well.  not much but it is helping.

[Doug]

So have you removed the Tstat? If you take that out the water pump impeller is visible up in the casting hole. Try spinning it with your finger or a piece of dowelling while holding the pulley. If it doesn't slip I would assume that it is still good. Mine was metal but some are plastic. Maybe it is time to replace the rad but I would flush the rad with a high volume of water first.

[jtanguay]

well i'm going to be buying a WP from ctire as well as an alternator pulley...  i figure that i'll check the impeller on the WP first and if it spins i will definitely change it... if its nice and solid with the pulley then I will consider biting the bullet to see if it works...

i have full confidence that its either the expansion cap or the WP.