Breakdown Diagnosis

P

pp1600

Member
The E86 coupe broke down on me today and required a tow back home by the AA.

I have a few ideas but looking for enlightenment from the Z4 knowledgable as to what to get fixed. How things unfolded...

A month ago i heard water 'gurgling' from behind the dash.this carried on for a few days then cleared itself never to return.Coolant level was okay.

Last week the coolant level light came on. Topped up and used for a few days to access the situation (small journeys) but still requiring top-ups.

Saturday replaced the expansion tank to rule that out as there was no overheating issues.
Bled the system and ran up to temp and all seemed good.

Today checked the coolant and was low. Topped up and decided a run is needed to fully test the leak. on the run she conked out..

The yellow EML light came on and the Exhaust Emission Values light. The car lost power.
luckily a lay-by (on motorway) was 50m ahead so pulled in and just as the car came to rest it cut out. It was a rainy day.

The AA checked the codes and a water pump run error came up along with multiple cylinder firing errors.There were a few others (should of taken note of them all!) but all codes cleared and an engine start showed no errors and no warning lights. it sounded like missing on 1 or more cylinders... but no codes came up.The firing showed all present but with varying percentages.

After being towed home we checked the running again and it was as if nothing was wrong!

Ive stuck to the facts so as to not colour the diagnosis.

What do you think?
 
Water got in to the electrics somewhere. The vanishing coolant may or may not be related.
 
buzyg said:
Water got in to the electrics somewhere. The vanishing coolant may or may not be related.
Click to expand...

My first thought was this has nothing to do with the coolant loss unless it was a head gasket. But I would have had other signs.

The thing that threw me later was the water pump run error.. does this show when coolant level is low?
 
Smartbear said:
How many miles has your car covered? The electronic water pumps are on thin ice after 70k :?
Rob
Click to expand...
Smartbear said:
How many miles has your car covered? The electronic water pumps are on thin ice after 70k :?
Rob
Click to expand...

Im coming up to 170 thousand. Car is and has been well cared for. Ive never known if the pump has been replaced at all ...

Time to replace regardless? plus thermostat?
 
pp1600 said:
Smartbear said:
How many miles has your car covered? The electronic water pumps are on thin ice after 70k :?
Rob
Click to expand...
Smartbear said:
How many miles has your car covered? The electronic water pumps are on thin ice after 70k :?
Rob
Click to expand...

Im coming up to 170 thousand. Car is and has been well cared for. Ive never known if the pump has been replaced at all ...

Time to replace regardless? plus thermostat?
Click to expand...

I’ve never heard of a pump lasting that long, could be the 2nd flaking out? :?
Others will say change both, if the thermostat showed no sign of trouble I’d be inclined to only change the pump.
Rob
 
Ive just had a look at the report and noticed a temp of only 29 deg was registered. I had only been on the road 10mins but 29 deg!!

Is the temp sender in the block or rad?

Im thinking water pump failure plus water in the electrics... I'm hoping the coolant is at the right height when I re-check it at least..
 
It tends to be the control electronics inside the water pump that die, this can mean the pump runs when it shouldn’t which means the car didn’t heat up properly. I normally don’t recommend changing the stat at modest mileages but in your case I would change both. I’m 99% that will sort the problem.
 
If there was an error code for water pump run error I think you definitely need a new water pump.

My 1st one died at 60k miles so your car has probably had at least one before!

You want a Pierburg one, but don't buy from BMW as they were charging just over £500 for them in 2015 - you can get them from other places, like Euro Car Parts, etc.

So far as the other error codes are concerned, do you know what condition your battery is in? These cars seem to throw up random fault codes when the battery is getting weak, even if it does still manage to start the engine. My next Coupe showed an amber EML and went in for diagnosis which turned out to be for post cat o2 sensors but the battery died during the diagnosis! New battery, codes cleared and all good 3 years later.
 
You also get multiple cylinder firing errors when the engine severely overheats but they seem incredibly robust when it comes to permanent damage, even when cooked. I would check all your spark plugs though, which may have suffered....that or a coil pack. Anyway, get that pump changed before you do anything else. Don’t drive the car as it is.
 
Can the water pumps also leak when they fail? That could explain the coolant loss.

How much coolant did you lose? It must be going somewhere. Any evidence of leaks?
 
Thanks for all the feedback.

The pump change and the thermostat shall be first.
The battery seems fine. Never shown any sign of giving up but ill check.
I haven't had time to recheck the coolant level yet but fingers crossed it was the expansion tank. level was good after being towed home.

A full service is due so I might go with some new coil packs also.

All of the jobs I can do but it would be great to hear of any well respected, knowledgable independents near Grantham.
I have previously had it serviced at Sopers near Lincoln but due to free time getting thin on the ground, and a few more items i'd like to have done, i'd like to lessen the expense...

Ive had a few places mentioned but it would be great to get a bit of feedback from the forum on real experiences.
 
I'm not local to you, but this might be useful:- https://www.pistonheads.com/gassing/topic.asp?h=0&f=72&t=796191
 
just to update.....

Pierburg pump and mahle berh thermostat fitted. With the new expansion tank fitted also it bled up easily.

The battery was checked and in good health.Plugs are fine. The car is running well so decided on no coil pack required.

I found a local independent BMW specialist near Cranwell (lincolnshire) so had an oil service.

The car has had a few long runs since and glad to report no coolant loss at all.

It has made me think about the failure rate of these pumps... mechanically they're sound and fail on the electrics... when I get a moment Ill look at the manufacturing date stamp on the old pump to see if i can tell wether it was the original pump.

also have a look at the electrics and see whats involved. Has anyone done this to see if a refurb of this pump is a viable option? This would be worth knowing to all fearing the pumps failure and the cost....
 
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