bugger

Patrick · #1 8th April 2008, 20:02

Was out for a drive today again as it was still sunny, unfortunately the
engine over heated after 30 miles - only for a very short period of time
maybe 30 second before I noticed. Let it cool but it seized up - balls.

Been towed home (not too far luckily) so this weekend will be take the engine to bits again time!

Took the plugs out and it is possible to turn it over so I'm hoping it's not
too bad. Ran fine for 250 miles!

At least it still has 4 wheels this time

MartinClan · #2 9th April 2008, 07:36

Quote:

Originally Posted by Patrick

Was out for a drive today again as it was still sunny, unfortunately the
engine over heated after 30 miles - only for a very short period of time
maybe 30 second before I noticed. Let it cool but it seized up - balls.

Been towed home (not too far luckily) so this weekend will be take the engine to bits again time!

Took the plugs out and it is possible to turn it over so I'm hoping it's not
too bad. Ran fine for 250 miles!

At least it still has 4 wheels this time

Thats odd. It normally takes much more than that to seize an engine. Was the oil pressure still OK?

Robin

Patrick · #3 9th April 2008, 07:39

Oil pressure was fine around 2 bar at the time. Won't know more till I find some time to take a few bits off.

Water didn't boil over which was strange and when I turned the ign2 on it had dropped to 80c very quickly.

If the temp goes anywhere near 100 it should be shooting out the header tank which it wasn't.

I'm wondering if my new water pump failed or if maybe the thermostat failed.

GreatOldOne · #4 9th April 2008, 07:39

Hope everything is OK - but it's a bit worrying...

Could this be due to your engine conversion? Does a 2.7 put out that much more heat than a 2.5? Or where you giving it the beans?

Pete's 2.0 overheated due to a stuck thermostat - But I seem to recall you changed yours out.

Patrick · #5 9th April 2008, 07:43

Tested the thermostat before putting it in and it was fine, but maybe it did fail. The water pump did make funny noises when first started but that seemed to clear up quite quickly.

The 2.8 will be making more heat but I've not been pushing anywhere near its limits as it's newly built, was driving mostly tiny country lanes at speeds between 20 and 40mph in 3rd and 4th so nothing too stressful.

MartinClan · #6 9th April 2008, 11:27

Quote:

Originally Posted by Patrick

I'm wondering if my new water pump failed.

Would seem the likely scenario to me - specially as you say it was making a strange noise.

Still odd that the engine should seize in such a short time. Years ago my (then yet to be) wife drove her 850cc Renault 4 from Maidenhead nearly all the way to Swindon with virtually no water before it finally gave up LOL.

Robin

Patrick · #7 9th April 2008, 11:30

I'm thinking the tolerances on the 2.8 are much smaller than on the standard engine and with new shells throughout yet to be worn in.

If I have no joy with the M20 I may look at ebaying a newer BMW 6 pot.

MartinClan · #8 9th April 2008, 12:21

Quote:

Originally Posted by Patrick

I'm thinking the tolerances on the 2.8 are much smaller than on the standard engine

Certainly than on a 100,000 mile R4!

Quote:

Originally Posted by Patrick

If I have no joy with the M20 I may look at ebaying a newer BMW 6 pot.

Might be a good idea anyway - you can then work on the 2.8 at your leisure.

Robin

Patrick · #9 9th April 2008, 13:35

Richard had some time to take a look at lunchtime -

Quote:

I can hand crank it fairly easily now, it does seem to get a little notchy in places.

Also the starter can turn the engine over however I have to hand crank it a few time first.

I did noticed the oil pressure went really high after a few turns of the starter

Maybe we have a blockage somewhere.

Patrick · #10 9th April 2008, 18:45

Thermostat is fine, water pump seems to be pumping OK, but not pull it out yet (rad is in the way). Oil in the bottom was quite dark but not clumpy. Oil in the top was still quite light.

When you crank the engine on the starter a few seconds the oil pressure goes way way up - I stopped at 6 bar.

So me thinks there's a blockage somewhere. Not pulled the sump off yet, but that's the next step.

MartinClan · #11 10th April 2008, 08:01

Quote:

Originally Posted by Patrick

When you crank the engine on the starter a few seconds the oil pressure goes way way up - I stopped at 6 bar.

That's very odd. Shouldn't the oil pressure relief valve (in the take off for the oil cooler) prevent excessive oil pressure? I think your diagosis might be correct - you have a blockage somewhere. Did you have any machining done on the block - perhaps there is some swarf in an oilway?

Robin

limpabit · #12 10th April 2008, 08:20

Sorry to here about this Patrick.

Hope you get it sorted soon.

Patrick · #13 10th April 2008, 08:51

Quote:

Originally Posted by MartinClan

That's very odd. Shouldn't the oil pressure relief valve (in the take off for the oil cooler) prevent excessive oil pressure? I think your diagosis might be correct - you have a blockage somewhere. Did you have any machining done on the block - perhaps there is some swarf in an oilway?

Robin

No machining on the block, only a skim on the head. The oil return will be the first item to check once the sump is off - follow by the main shells.

The oil filter seems heavy (but then its saturated) so I may chop it up see if I can see something in there.

Patrick · #14 10th April 2008, 18:44

Some progress this evening

On inspecting the sump it turns out the ring terminal for the earth strap has broken, it was in place so that you could not see it had broken. There was a bit of contact but not much. This is the cause of the high oil pressure. Not much earth gauge OK when you put it on ignition 2, run the starter and it screws that up so the pressure goes up. Disconnect it and no earth = gauge on highest setting.

The also means the starter does not run properly as it doesn't get enough power.

Took the sump off. No obvious marks in any of the bores from the bottom. Push in the oil return and the oil runs out fine, oil pump seems to be OK.

Added a temp earth strap and now the starter runs fine turning the engine over without any problems (no plugs) - no odd sounds from it either.

Hypothesis is airlock (driving up hill), overheat and then unable to run anything due to the earth strap.

Seizing probably due to small tolerances and overheat. Need to pull a cap off check a shell for damage.

Doesn't look as bad now as it did initially. I'm going to do have more of a look around, get a genuine water pump from BMW as the one I have makes a noise and a new sump gasket, new oil and filter and see how it goes.

peterux · #15 10th April 2008, 20:21

So I guess the question is, did it really seize up?

Was the rise in temperature also an electrical problem like the oil gauge?
If you didn't loose any coolant, it couldn't have got very hot.

If your earth strap was about to fail, the starter wouldn't pass enough current to turn the engine, maybe making it appear to be siezed up?

It might also be worth checking your radiator fan is also working correctly.

Looks like you'll be back on the road again soon.......

Peter

Patrick · #16 10th April 2008, 20:34

It did seize up as we couldn't push it in gear, which kinda bugs me unless the starter locked somehow ? . Tested the fan and thermostat both are fine.

Good question on the temperature, however that stayed on 0 without an earth.

I do hope we're on the road again soon

GreatOldOne · #17 10th April 2008, 22:10

Quote:

Originally Posted by Patrick

On inspecting the sump it turns out the ring terminal for the earth strap has broken, it was in place so that you could not see it had broken.

Just out of interest, where is the main earth strap for the engine?

I can't for the life of me remember disconnecting an earthing 'strap' from the engine to the chassis when I took the engine out the donor - the only earthing point on it I can recall is the bundle of brown earths that bolt to the intake manifold under the diagnostic connector bracket.... And that's part of the engine loom. Not what I'd call a strap at all - not like item 14:

http://www.realoem.com/bmw/showparts...55&hg=12&fg=31

Which seems to be described as item 13 on the parts list!

Patrick · #18 10th April 2008, 22:17

You know where the level sender is in the sump (passenger side) there is room there for a 13mm bolt which is the earth

On the donor it bolts to the engine mount IIRC.

It is part 14 in that diagram. I've looked at the model year of my donor and found this:

http://www.realoem.com/bmw/showparts...61&fg=10&hl=18

GreatOldOne · #19 10th April 2008, 22:23

Good job I asked. I don't have one!

Patrick · #20 12th April 2008, 13:31

Taken the water pump out, it looks fine. No damage or wear marks.

Also taken several main bearing caps off and check the shells. They all look OK slowly starting to wear off the protective layer - no obvious damage.

Next step is reassembly, new earth strap, new oil and a new filter. Fingers crossed it will run OK again.