Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[kenlyn]

Hello
I am a new member seeking assistance with a new fault on my omega 2.5td auto saloon 1998.
Yesterday for no apparent reason temp gauge shot up into red danger area. water level ok, oil level ok with no sign of water in oil.
Water hose leaving thermostat felt cold although engine very hot.
A very little water had come out of expansion tank pressure cap.
water inside expansion tank very clean.
Does this suggest a thermostat stuck CLOSED ?
Any help appreciated
YRARCH

[Marks DTM Calib]

This over rated BMW lump has a number of more common cooling issues.

The most common failure is the water pump where the vanes snap off and the symptoms you have sudgest this might be the case.

Key thing i not to use it or you risk cracking the head (seen this a few times) and even throwing a rod (also seen this to!).

Other things to check are the rad (once the water pump is sorted) as it has a habit of silting up on the tractors.

[Pitchfork]

It could be a thermostat problem but also the water pump may have given up & shed a fin or 2 from the impeller
The bearing in my pump failed recently (causing the drive belt to fall off) and the temperature to go of the top of the guage within 500 metres
According to The Boy who has intimate relationships with the BMW lump, pump failure is not uncommon. I'm sur that he will wish to add his experience to the matter
IW

[TheBoy]

Having fought my tractors cooling issues all last year, I would follows Marks_DTM's diags above:

Remove water pump, check vanes still in place. If not that, check for exhaust fumes in header tank.

Also, do not use - these engines are 'safe' to 110C according to bMW, and that is about 100C on the gauge (and the gauge is 12s behind actual).  Beyond this, the heads are very prone to cracking.


As M_DTM said, rads prone to silting at around 120k

[kenlyn]

Thanks for replies today, and my mileage is 121k.
No previous trouble and I tow a 1430kg caravan. 330 mile round trip during easter went with no suggestion of overhating!.
Decided to check thermostat tomorrow, as having started car again today, and watching the temp rise past 100*, the pipe leaving the thermostat was cold which suggests to me now that the stat has stuck closed.
Will keep you informed
Thanks

[TheBoy]

Thanks for replies today, and my mileage is 121k.
No previous trouble and I tow a 1430kg caravan. 330 mile round trip during easter went with no suggestion of overhating!.
Decided to check thermostat tomorrow, as having started car again today, and watching the temp rise past 100*, the pipe leaving the thermostat was cold which suggests to me now that the stat has stuck closed.
Will keep you informed
Thanks

While you're there, check the water pump for an in tact impellor.

[Marks DTM Calib]

Thanks for replies today, and my mileage is 121k.
No previous trouble and I tow a 1430kg caravan. 330 mile round trip during easter went with no suggestion of overhating!.
Decided to check thermostat tomorrow, as having started car again today, and watching the temp rise past 100*, the pipe leaving the thermostat was cold which suggests to me now that the stat has stuck closed.
Will keep you informed
Thanks

Interesting, never seen a stat fail closed, they are designed to fail open.

Remember that for the stat to open it needs coolant circulating over it...

[TheBoy]

Thanks for replies today, and my mileage is 121k.
No previous trouble and I tow a 1430kg caravan. 330 mile round trip during easter went with no suggestion of overhating!.
Decided to check thermostat tomorrow, as having started car again today, and watching the temp rise past 100*, the pipe leaving the thermostat was cold which suggests to me now that the stat has stuck closed.
Will keep you informed
Thanks

Interesting, never seen a stat fail closed, they are designed to fail open.

Remember that for the stat to open it needs coolant circulating over it...

Certainly my diesel one failed open...

[kenlyn]

Hi everyone

Removed thermostat about an hour ago, but before testing in a boiled kettle ,decided to stick my finger into the engine block and check the pump impellor as some of you suggested. Yes you were correct, the impellor was in bits with every vane broken off. Due to having had to tap( gently) to remove the stat, I have decided to put in a new one of these as well, as MY OLD FAITHFULL OMEGA has served me well over the last 8 years.
New pump and stat will go back in on Friday and I will report back afterwards. Great forum, should have found it sooner,but not had cause to.
YRARCH

[Pitchfork]

Hi everyone

Removed thermostat about an hour ago, but before testing in a boiled kettle ,decided to stick my finger into the engine block and check the pump impellor as some of you suggested. Yes you were correct, the impellor was in bits with every vane broken off. Due to having had to tap( gently) to remove the stat, I have decided to put in a new one of these as well, as MY OLD FAITHFULL OMEGA has served me well over the last 8 years.
But where have all of the broken vanes gone?
New pump and stat will go back in on Friday and I will report back afterwards. Great forum, should have found it sooner,but not had cause to.
YRARCH

[TheBoy]

Hi everyone

Removed thermostat about an hour ago, but before testing in a boiled kettle ,decided to stick my finger into the engine block and check the pump impellor as some of you suggested. Yes you were correct, the impellor was in bits with every vane broken off. Due to having had to tap( gently) to remove the stat, I have decided to put in a new one of these as well, as MY OLD FAITHFULL OMEGA has served me well over the last 8 years.
New pump and stat will go back in on Friday and I will report back afterwards. Great forum, should have found it sooner,but not had cause to.
YRARCH

Glad you've found the issue, hopefully no other damage done.

[kenlyn]

Hi all
As a matter of interest, my local motor factors sent me out a new pump this morning and it has a cast iron impeller. The plastic one on the old pump had disintegrated and must have age hardened and become brittle!! But had lasted 121k miles , so can't complain.

[Marks DTM Calib]

They often fail long before that!

Try to reverse flush the block with a hose pipe to get the bits of impellor out.

[kenlyn]

Thanks for suggestion to remove damaged impeller vanes. Ishould have mentioned dooing this and all broken bits accounted for.