Overheating

[latrine]

yes, that old problem again

 

I'm confused though!

 

my Gal started overheating tonight when under load

 

On tickover/gentle driving the temp guage sticks at its usual 90 degrees, but when under load rockets upto to the red line

 

have read the threads on this forum and seen the various issues that may cause this but by my (very basic) way of thinking, i would have thought that any problem with the thermostat or mechanical water pump would cause overheating even when not under load

 

I think my problem is with the auxhiliary water pump (the electrical one) as it has died a death the last few days - it had been getting noisier over the last few weeks and now i know it is not running as there is no noise at all after the engine is switched off

 

please can someone tell me if I am right in thinking that the mechanical water pump alone is sufficient to keep the temp at 90 on tickover/gentle driving, but at load, the engine needs the additional benefit of the aux pump?

 

cheers all

[bigdaddy]

How about vehicle details,,,,,,,,,,,,,,,,,,,,,

 

 

 

IIRC the aux pump is for when your engine is hot and turned off,,,,,,,,,,,,

 

If your engine tewmp is redlineing,,,,,why are your fans not coming on, the fans should stop it redlining, if they work then you are seriously low on coolant or the thermostat is stuck in the closed position or your temp sensor to the ECU has failed,,,,,,,,,,,,,,,,,,,,,

 

An engine will get hotter when under load,,,,,,,,,,,,,,,,,,,,,,,,,

[latrine]

Hi BigD

 

i've changed my signature now - it should show that the Gal is a 1.9 tdi - it's manual and the 115 engine

 

 

 

I thought i read somewhere on this forum that the aux pump runs whilst the engine is running, not just after switch off

 

the fans are working fine, and the coolant is fine too

 

i'm certainly no expert, but my understanding is that if the thermostat was knackered, the temp would just keep rising and rising - my problem is that the temp rises, as normal to 90 degrees, and normally doesn't budge an inch from that - however, yesterday, after about 3hours of driving, the temp all of a suden went up to the redline - i stopped and the temp immediately dropped back down to 90 and stayed there whilst the car was on tickover, or driven very gently

 

however, when i put the engine under load it rised back above the 90 and head towards the top end unless i ease off - can the themostat partly work?

 

finally, can you tell me sorry what IIRC means? - i'm not fully conversant with this text speak and i see it a lot on this forum

 

cheers

[tiny]

IIRC If I Recall Correctly

 

I had to ask that one too (Cheers MM)

[roly1977]

i had that with mine turned out to be head gasket over

[latrine]

gee thanks!

 

IIRC (!) though, would there not be water in the oil if it was a head gasket problem? and is the tell-tale sign of this gunge/froth in the oil?

 

i checked the oil out and round the filler cap and all seems fine - car is also running like a dream bar this overheating business

 

i'm grateful for all the responses to date and future responses

[roly1977]

mine didnt have water in the oil or any grunge in the cap all i noticed was when i undone the water cap it chucked water out my garage did the test for exhaust gasses in the water system and there was

[MatTdi]

I had the exact symptom and it was the waterpump, the impeller had detached from the shaft. see attched image.

I even had one grage trying to tell me that the head gasket had gone :D and we wonder why garages get a bad name....

 

Its a cambelt off job to change the pump so if your near that time I would get the belt, tensioner and pump changed.

 

If you want anymore info on my symptoms give me a shout

 

M@

[latrine]

cheers Mat

 

it's booked in for the stat chnge tomorrow - i'd rather try and elimante the cheapest options first!

 

will post an update once i've got the Gal back

[latrine]

Ok - now had the stat changed - no difference!, still overheating under load

 

Will now consider the water pump (together with cam belt change)

 

However, IIRC, could the problem be the temp sensor? - is this the sensor attached to the bottom of the water bottle or is this just the coolant level sensor?

 

how easy/expensive is it to change the temp sensor?

 

look forward to receivieng your replies, thanks

[latrine]

Just to sign off this thread, i can inform you all (or those that are interested) that i went with the change of water pump (and change of cam belt at the same time)

 

turned out to be exactly the problem Mattdi identified - namely, the impellar becoming detached from the rest of the pump

 

the new pumps are fitted with a metal impellar so hopefully, there won't be a repeat of this problem

 

gal is now running fine again, with the temp refusing to budge above 90 degrees

 

thanks to this forum, i was able to diagnose the problem myself and just used the garage to fir the parts

 

cheers

[Guest seacam]

Just to sign off this thread, i can inform you all (or those that are interested) that i went with the change of water pump (and change of cam belt at the same time)

 

turned out to be exactly the problem Mattdi identified - namely, the impellar becoming detached from the rest of the pump

 

the new pumps are fitted with a metal impellar so hopefully, there won't be a repeat of this problem

 

gal is now running fine again, with the temp refusing to budge above 90 degrees

 

thanks to this forum, i was able to diagnose the problem myself and just used the garage to fir the parts

 

cheers

 

Good to hear,

 

How much did it cost you in all to fix?

[MatTdi]

Latrine,

Glad to hear I was able to help you get it fixed, its nice to be able to return the favour of all the help this forum has given me along the way!!

 

Now all i have to fix is the dreaded air con again!!!

 

 

Take it easy

 

M@

[Scorpiorefugee]

And another one....

 

Just got back from Devon, up the M5 at 60mph with the heater full on. I'd already guessed water pump and here it all is - very reassuring and thanks to one and all.

 

Just the bad news, bought in Nov 2005 with one year's third party waranty, took delivery on 16th Dec but it looks as if the warranty was dated to purchase date. &@#N!. Also, had the cam belt changed in the first month of ownership 'cos they sold it with 70k, dealer service from new and no evidence of a previous change!

 

Mind, average fuel consumption on the way back - 57 mpg, going down - 38 mpg at 75 mph ?????.

 

If I drove like this for another 20,000 miles, I'd probbaly save enough to pay for the repair....

[Guest gooner52]

And another one....

 

Just got back from Devon, up the M5 at 60mph with the heater full on. I'd already guessed water pump and here it all is - very reassuring and thanks to one and all.

 

Just the bad news, bought in Nov 2005 with one year's third party waranty, took delivery on 16th Dec but it looks as if the warranty was dated to purchase date. &@#N!. Also, had the cam belt changed in the first month of ownership 'cos they sold it with 70k, dealer service from new and no evidence of a previous change!

 

Mind, average fuel consumption on the way back - 57 mpg, going down - 38 mpg at 75 mph ?????.

 

If I drove like this for another 20,000 miles, I'd probbaly save enough to pay for the repair....

 

the fuel consumption was very good for you then,sounds pretty good to me also ;)

was the warranty 3years or 60k

[Scorpiorefugee]

Hi Gooner,

 

Sadly, bought S/H, the only warranty was a 12 month Insurance type thingy and they may have already coughed up for the cam belt change If I know anything about the way dealers frig these things.

 

I've just booked it in at my friendly, totally trustworthy, local who told me that they routinely change the water pump on most vehicles when the do the cam belt.

 

Re the fuel...

 

It seems an enormous difference for the 15mph change in speed. I used the cruise control in both directions. It could be something to do with the prevailing South Westerlies though as I have noticed a conisderable difference on the same 400 mile return trip in the past. Sadly, this newer ,52 reg, doesn'e normally come even close to the economy figures I get from the old 98 banger.

 

Regards,

 

Ron.

[Guest gooner52]

what economy figures did you get out of the 98 model

[Scorpiorefugee]

The old 110 is a good 5MPG better than the 115. On a good day I can get 46/47mpg over a tank full but the 115 rarely manages better than 40. I did once get more than 750 miles on a tank full but that was living dangerously. Both are a lot better off the motorway in spite of the 6th gear on the 115 unit and the steady cruising speed so there does seem to be a sudden leap in consumption above 60/65. If I push it up to 80 ish it drops to 43/44 or 37/38 on the newer 115. I usually find it's almost exactly 10 miles per litre over several full tanks.

 

I keep meaning to swap the MAFs over just to check but, beyond that, everything seems clean and tidy. The only other real difference is that the newer one has been serviced regularly by the main dealer (before I got it!) whereas the old heap has done 180K plus with little more than an occasional wipe down with an oily rag.

[Scorpiorefugee]

Back to main topic on this one again.

 

The good news is that my overheating problem was fixed quickly, thoroughly and cheaply (

[Guest mcyoungy]

Bottom cambelt pulley? Isn't that on the crankshaft? If this is damaged it will reduce the life of the belt. Sounds like it may have become damaged by the belt not being tensioned properly.

 

What sort of mileage are we talking for water pump failures?

[Scorpiorefugee]

Mine went at 75K.

 

I had a BMW 525 that lost one at 170K but that was probably brought on when I had to go to 7000 rpm in 1st to get out of the way of a lunatic that came round an island at me at about 70mph. :wub: :16: :16:

 

I have no information on the others but I am told that it is quite common and my garage is getting close to routinely changing them with the cam belt.

 

As far as the pulley is concerned, I think that it is outside of the timing belt cover but cannot be sure and it is held on with bolts 'co they have already got replacements for them.

 

I think the important message relating to the water pump failure is to slow down and set the heater on full to get you home while watching the temp.

[tim-spam]

The lower crank pulley is also a vibration damper, and is a bonded rubber / metal construction, so I suppose that it could be becoming delaminated - never heard of this happening before though.

 

However, Eurocarparts sell them (which means that it must happen sometimes) - OEM

[Scorpiorefugee]

Tim-spam,

 

Sounds like you've got it in one. Your descriotion matches what my mechanic tried to tell me.

 

I shall pass the info on.

 

Very many thanks.

 

Ron.