Bleeding help. Non standard engine change

[tommobot]

I've recently installed a BMW M52 (6cylinder petrol) into my defender.

As far as possible ive tried to match the OEM (south Africa spec) cooling setup where this engine is standard.

For the life of me, I can't get an air lock out of the system.

Bleed points, top of rad, coming out of engine before top hose, just before back into engine and before heater box up top.

Any tips, ideas, thoughts welcome..

[tommobot]

More photos

[tommobot]

Temp gauge says overheating..

Top hose super hot..
Bottom hose ambient temperature.

Brand new rad, new water pump, new heater matrix and thermostat.

[tommobot]

Pretty basic drawing, to accord with the photos.. the cooling system dips into the throttle body for an unknown reason (OEM)..

[tommobot]

GreenV8S said:

Sounds like you have low / no flow through the rad.

How is your pump vented?

Oops, missed that off the sketch.. there a small nipple from the rad, feeding back into the header...

[tommobot]

Oh god.. that's a bit confusing..

The water pump arrangement is as per OEM... This engine was in another defender before working perfectly, and I've almost had it working properly before.. but think that was pure luck..

I was thinking of getting a metal thermostat housing and putting 2 bosses in it to act as bleeders....

[tommobot]

My setup is a bit different to the 5 series, but I assume jack it up.. leave the rad bleed point open and header tank open aswell?

[tommobot]

Haven't checked it against something, but pretty confident if not utterly confident it's an airlock..

Tried again today... No temperature raising in top hose, throttle body hoses v.hot... removed top hose from housing slightly and water started flowing into rad..

Still nothing at bottom hose. Stone cold.
Took out temp sensor/bleed valve on the bottom hose. Could physically see the stationary cold water.

Also no heat to heater hoses arghhh...

Pressure kits, are we thinking this sort of thing?

Think I'll drain tomorrow and refil via heater hoses....

Was trying today with front end on Ramos, header tank closed and a funnel in the rad bleeder full of water etc...

[tommobot]

GreenV8S said:

Is there pressure in the top hose or just stationary hot water? If there's no flow or almost no flow, that suggests there is no coolant circulating or the stat isn't opening. An air lock in either component would account for that.

You really need to look at the layout of the water pump and stat housing and understand how they are connected. It should be pretty obvious once you see how the bottom hose connects to the pump inlet. The first thing to determine is whether it has a top stat (connected to the top hose) or a bottom stat (connected to the bottom hose).

The thermostat is connected to the bottom hose... as shown below.

How can I actually tell as such if there is pressure in the top hose? - Resistance to squishing?

At first there was no flow whatsoever, whilst running I slightly slipped off the top hose from the housing, a load of air came out and you could feel the water rush into the hose, and the hose instantly got hot, as did the rad and the water could be seen pumping through the rad bleed nipple.

I couldn't make it come back up the bottom hose, as this remained stationary.

It seems like its almost worth taking the stat out to test and see if it circulates!?


Generic M52 image:

[tommobot]

Oops, just realised I forgot to put the link into the pressure bleeder thing...

https://www.ebay.co.uk/itm/General-Radiator-Pressu...

This sort of thing?

[tommobot]

d_a_n1979 said:

The states duff/failed... Fit a new one (Walher ideally) and it should be fine

Jack the front end up and bleed the system properly; air will come out then (heaters on full whack etc).

Folk say the E39s are hard to bleed; but never had any issues with mine

Good info here: https://www.bimmerfest.com/threads/diy-bleeding-th...

Key is having the front end up a few inches

Its got a new stat in it, and a new water pump.. The front is currently jacked up

Arnie Cunningham said:

Have you bled the heater too? On mine (Rover V8) the stat didn't open until I warmed up the motor a bit (not too much, mind, but enough to get a little system pressure), and then loosened the hose clips on the heater. A burp of air followed by a dribble of water and suddenly everything was OK again - stat opened, rad got full flow and all has been fine since.

I've tried to bleed it, it was working fine I.e the pipes getting hot, but with my persistence to get full flow now it appears that water is not flowing to the heater...

I.e, if I take the hose off whilst running water doesn't piss out... I've installed a small bleed valve in line to the heater matrix.. but still nothing...

I would suggest that maybe the issue is that the heater matrix is higher than the header tank? - But then that's surely the same on every land rover every made, and the factory M52 defender.

Perhaps worthwhile unfitting the header tank, and temporarily bodging it so that its absolutely the highest point. Also, the engine is slightly off rotation from BMW spec, maybe by 11 degree or so... could this be causing issue somehow?

[tommobot]

I've put a small 2mm hole in the stat already.. made no difference..

[tommobot]

I haven't tried it without the stat..

Don't think rad weld has been used, would be fairly confident previous owner would stay away from thermostat / water pump from local motor factors..

Am I right in thinking of I plonk the stat in boiling water after a while I should see it open up ?

[tommobot]

AW10 said:

I'd go back to basics - take the rad out and ensure there's flow through it. Put the thermostat into boiling water and ensure it opens. Run the car without a thermostat and see what happens.

That definitely looks to be an M52 engine. With the intro of the M52TU BMW went to a thermostat controlled by the ECU but the M52 should have a standard thermostat. Any chance an M52TU stat was fitted? (no idea if they're physically interchangeable)

Which reminds me of another issue that used to affect the Ford Zetec engine (mid 90s Mondeo lump) when installed in a Caterham etc. Can't recall the exact details but one company's install required the drilling of a small bypass hole in the thermostat otherwise the hot coolant from the engine couldn't reach the thermostat because there was a "plug" of cold water in the way. The bypass hole allowed some flow through the stat so that the hot water could reach it and make it open fully. Could you have a similar issue?

I'll take the stat out and test it later.

As far as I'm aware the M52TU is an electronic stat, so I would have thought they are physically and mechanically different?

I've drilled a tiny 2mm hole in the stat to at least allow some water to circulate in theory.

I'm 99% confident that rad is working fine. As noted earlier, the car was working fine and I took it out for a drive and temperature stayed normal. With help I managed to get it bled by just pure luck, but we suspected the water pump may be nackered - It was, put a new one on and its been woefully airlocked ever since it appears!

If i'm taking the stat out to test it, I might aswell fire it up and see what happens...

[tommobot]

Stat is working fine...

[tommobot]

AW10 said:

I'd go back to basics - take the rad out and ensure there's flow through it. ?

I'm guessing unplug each end, blast a hose pipe through it should be sufficient for this?

[tommobot]

Another wasted afternoon.

Right, so rad is fine, flows ok.

Water flows with thermostat out.

Put stat back in, refilled from heater pipes.

Ran and revved for 10min or so.

Top hose hot, rad hot, bottom hose cold.

Opened bleed valve before stat water gushes out... Last time it was empty and stationary.

No heat to heater pipes... Put header tank cap on.. and sealed system to run for min or 2...

Opened OEM bleed valve on thermostat housing.. nothing, no water bone dry ... Turned off engine as could only assume catastrophic failure.

Slow trickle or water, untightened header tank, water rushes and comes pissing out.

Help!

Now I'm completely stumped.

Maybe just get a pressure testing kit, I have no f'ing idea any more

[tommobot]

If I disconnect the top hose water comes pissing out...

Tbh, it could just the residual water behind spewing out.. how could I realistically test.. it's brand new so should be ok..

[tommobot]

Old one had failed, and was plastic..

New one was metal..

[tommobot]

A couple more thoughts..

I'm wondering if I have got enough coolant mixed in.. does adding coolant add thickness to the water?.. on the basis that I'm emptying the system every other day it seemed a bit pointless / wasteful.

It's probably very weak coolant %.

I'm reading on bimmer forums people experiencing similar issues, basically saying blow into header tank with bleed nipple open.

Surely this is basically the same as one of these coolant pressure testing kits?....