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[Spearmint]

Hey guys,

1999 2.5TD (BMW Engine) CDX Auto.

Right then, car has until just recently been sat for 4 months outside my garage as I was away with work. Shortly before I went OOA I changed the water pump and renewed the coolant due to the last water pump going U/S.

I've noticed now that the water temp has been higher than usual. Typically it sat at around the 80'c - 85'c mark even when it was pulling a full trailer. Now it's been sat at the 95'c - 100'c mark and today whilst pulling a trailer it nearly reached the red before I threw caution to the wind and shut her off for a few minutes.

Another thing is the other day with the temp reaching 100'c I hit a speedbump @ about 20mph upon which the water temp reduced instantly by about 10'c. So with that speedbump did I knock something loose? Perhaps some gunk in the radiator?

Fingers crossed this is a cheap fix as I've just spent 400GBP on it's MOT.

I'm thinking partially blocked rad so a remove, flush, refit, refill job?

Anyone agree?

Thanks in advance for any advice.

[Richard A]

Sounds very much like an 'air lock' to me 
Good luck
regards
richard a

[Spearmint]

Ahh ok. I thought this was a self bleeding system as I couldn't see any 'high point' in the coolant system from which to bleed the air out.

Is there a how too on here Richard?

[charlie]

ive changed the stat in mine, now runs 80-85, the guys on here say it should be in 90s and said change the water pump to hopefully have it in the 90s. so the increase in temp shouldnt be anything to worry about unless it hits the red

[Spearmint]

Cheers Charlie, Stat would be one of the things to change on my list if it's not the coolant system being blocked or suffering from an airlock.

[charlie]

i would try without the trailer. Give it thrashing see if it goes past 98 on the temp. if not i wouldnt worry

[Welung666]

Ignore the temperatures on the gauge, they are useless. It should sit around the centre of the gauge when hot if it creeps up then it's getting to hot.

To self bleed the system - from cold fill the coolant resevoir to the seam. Start it up with the heaters on full blast. Once it's getting up to the middle of the gauge sqeeze the 2 large hoses (minding fingers, clothing etc. on turning parts) a few times. Any bubbles coming out into the resevoir is the trapped air in the system. Once the heaters are blowing hot and no more bubbles are coming through refit the cap and off you go.

[Spearmint]

Thing is though, I was only doing a short hop across town to the tip. I sometimes use the trailer to pick up stuff from upto 120 miles away and as the car could do it no problem before I really need to get to the bottom of it.

[Spearmint]

Sweet, cheers Welung666. 

[Richard A]

Sorry went to lunch, do as 'Welung666' suggests.
regards
richard a

[Spearmint]

Tried as per Welung666's advice but to no avail.

Temps still too high on a short journey around town. Climbed to near 100'c after approx 10 mins then 105'c (The last white line before red) on the last 5 mins of the journey. It sat at this temp for around 2 mins whilst static outside the house until I switched the aircon on (Just to see if it would have an effect.) whereby the temp would have once again gone off into the red had I not shut her down.

I'm thinking blocked rad or maybe those fans at the front are U/S?

[Richard A]

At that temperture the all three fans should at least be running at slow speed, even if the engine fan on your 'diesel' a viscous type, do the two front fans run with the aircon on ?
regards
richard a

[Spearmint]

Took it on another journey just now. The temp wouldn't budge past just under 100'c. Parked up, switched the aircon on and I did notice that the two fans at the front aren't operating.

Held the revs at about 2Krpm for approx 30 secs and noticed that the water temp fell to around 90'c?

I'm going to fetch a spare battery and zap the fans with 12v, see if the motors have seized or anything.

[Spearmint]

Stuck 12v across the right hand fan which instantly spurred into life so they are ok.

The sender below the right hand (Fat) coolant hose, is that what the fans depend on for power? I only ask as I have 12v sat waiting at the plug for it.

Anyways, took the rad cap off and started her up from cold with the aircon on full heat. Idled her for approx 20 mins (Held her at 1Krpm for around 3 mins to see if any difference). Temp took about 15 mins to reach approx 85'c and then it didn't budge. Warmish air was felt from the vents.

So maybe I've got rid of the airlock if so? First chance I get I'll do another test drive.

[Spearmint]

Test drive complete.

Urban driving seen the temps rise to 90'c and then hold. Took her up to 60mph where the temp increased to 95'c but then held there.

Parked up, temps still held @ 95'c but the electric fans at the front still refuse to work.

Anyone know when these should come on?

I guess I've just got to keep chasing the air around the system till it finally bleeds out?