How do you test a 300tdi waterpump?

[L835]

My 300tdi is overheating. After it briefly put out a load of white smoke and the needle started heading for the red. I have -

Checked thermostat in hot water with thermometer - opened correctly

Flushed radiator - water ran clear

Bled cooling system - heater blows hot!

Changed head gasket. No sign of cracks between valves or around glow plugs/injectors. Head checked with straight edge for warping.

One mile from home and it is almost in the red again! Top 1/4 of radiator is hot, lower part icy cold.

So other than internal cracks in the head....all I have left to check is the water pump. Any suggestions on the best way to do this please?

Thanks

Richard

[Disco-Ron]

Take it off and check the rotor perhaps??

[Aragorn]

or just fit a new one, they're hardly dear, and if your pulling it off to check it, its sorta pointless refitting the skanky 10 year old part back on...

If it has a plastic impeller, they often snap and come loose from the shaft. When the one on my A4 went, it worked until the RPM's rose above about 1500, at which point it started slipping and water flow stopped. I could drive along just fine below 1500rpm, but if i took it up to 2000 the temp would shoot up. Drop below 1500 and it would come back down again. When i removed the pump there was a crack thru the hub section in the middle of the impeller, and while still attached to the shaft, it would slip if some force was applied.

[L835]

Thanks, looks like it's coming off! Logically it must be the pump, if I've cold water in the radiator and the head is red hot!

[bushwhacker]

As the others have said. My heater was running cold.

I had an impeller on a 300 waterpump come loose when it should have been solid on the shaft.

New pump sorted it. I bleed the system with the expansion tank raised as high as could get it, having read to do this somewhere.

[oneandtwo]

Buy a quality own one like quinton hazell. I put a cheap pump on mine last year as all I could get at short notice. Squealed as soon as it was fitted and bearings totally shot at well under 1000 miles.

[cookie64]

for the 5 years ive owned my 90 ive always had overheating problems

shes had new ;

2x rads

1x head

1x heater

4x water pumps

4x thermostats

2x tensioners

and annoyingly 6x alternators

all things wrecked by the ridiculous heat

i have just rebuilt my engine and replaced all the hoses and noticed that the small bore breather lines from top of rad and thermostat to the header tank were solid, now shes running again, i can actually see water movement in the header tank!!!! ive never had this before so think that the pipes may have caused a bigger issue than thought

just an idea to see if you have water movement in header tank and all the hoses are clear

oh also the reason for rebuild was because got too hot and boiled oil off causing pistons to viciously attack cylinders haha

tom

[mmgemini]

As the others have said. My heater was running cold.

I had an impeller on a 300 waterpump come loose when it should have been solid on the shaft.

New pump sorted it. I bleed the system with the expansion tank raised as high as could get it, having read to do this somewhere.

The correct way to bleed a 300Tdiis.

Fill the header tank to level and fit top.

Remove both the plug at the thermostat top and thew plug in the radiator.

Fill the engine with coolant through the thermostat housing until water flowes from the rad plug.

Squeeze hoses and keep rad flowing.

Fit rad plug.

Keep filling until the level is at the top of the thermostat.

Squeeze hoses to break air pockets.

Top up to level and fit plug.

CHECK header tank and fill to level if necessary.

Unless you have a South African radiator. The water will flow into the bottom pipe, up the tank and out the top. It will not flow through the matrix.

[L835]

New (genuine) water pump fitted. Old one seemed ok, not slipping on shaft etc.

Still overheating and on checking, found that the thermostat - header tank hose was blocked (so air had no way to escape from head.(many thanks Cookie!)

Bled as per mmgemini's method, but found heater was running cold. So, disconnected front hose from heater with engine running - nothing. Disconnected rear hose and water everywhere! (engine stopped immediately!)

Bypassed heater matrix and went for a spin, stopping on a 1 in 4. Low 1st to get up the hill, but needle stayed at top end of white on gauge!

Have flushed heater matrix, and will try again once bled!

[bushwhacker]

If you still have the four old thermostats check if they are working ok, pick out the best and stick it in, try filling and bleeding the system with the expansion tank raised. I honestly found this helped mine, youv'e nothing to lose. If that doesn't work run it with the thermostat out

.

Did you use new head bolts (or was the old ones reusable) and torque them down plus the degree turn if they needed that done?

A sheet of flat (obviously) glass new steel ruler and feeler gauge is a good way to check the head is flat.

Stick with it you'll get there.

Mark

[L835]

Thanks Mark, tested thermostat, but think the gauge and sender are miss-matched (separate thread on that!) as normal is the right hand end of the white scale. Thermostat opens in the black.

Managed to bleed system by cracking the x-cap on the thermostat housing after each run, heater blows hot and no coolant loss (so far!) Did re-use the head bolts, torqueing + angle. Just need to change the injector that seems to have given up then we're there!

[FridgeFreezer]

If that doesn't work run it with the thermostat out

That's not a great idea, run it with a stat with the middle cut out perhaps - you need a bit of resistance to stop steam pockets forming in the head.

Bit of a bold assumption, but is the stat a genuine one with the bypass hole/jiggle pin to prevent air-locks?

[Bowie69]

I think the 300TDIs is that horrid plastic thing don't they?

[FridgeFreezer]

I think the 300TDIs is that horrid plastic thing don't they?

Dunno, my interest in TDi's is minimal, just throwing a few blue-sky ideas into the think-wok. That and the symptoms are very similar to when I had a stuck / rubbish stat...

[Bowie69]

my interest in TDi's is minimal

Well, ditto Just seemed to remember it from another thread...

[TheRecklessEngineer]

I think the 300TDIs is that horrid plastic thing don't they?

Nope. It's a normal metal/wax type.

[western]

Td5 has the plastic cased thermostat.

[Bowie69]

Thank you!

[bushwhacker]

Good to read your making headway, let us know if the overheating problem is sorted.

Did you raise the ex/tank at all when bleeding?

I was at the stage with mine if the ex/tank raised hadn't helped it was the matches next.

[L835]

No I left the expansion tank where it was, but kept bleeding the thermostat housing. At working temperature the gauge sits at the left hand end of the white part of the scale, and no coolant loss. Given the narrow safety margin in 300tdi coolant levels, I am adding a low coolant alarm http://www.ebay.co.uk/itm/170927068334?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_1259wt_1255

[mmgemini]

So if the gauge sits on the left. What ACTUAL temperature is that ?

With a Land Rover Defender gauge with the needle in the middle. The actual temperature of the coolant could be 88 Deg C, OR it could be 96 Deg C, take the pick of what you want.

I always suggest before you start talking temperatures of an engine. You fit a full scale properly corrected temperature gauge.

[L835]

88 degrees. Tested the thermostat with a calibrated thermometer, and at the end of the scale the radiator is cold. Push the engine and the 'stat opens, radiator gets hot but needle stays roughly where it was. I'm putting it down to a mis-matched disco sender and defender gauge.