M54b30 blown hg due to faulty thermostat

[bmwdroptop]

Last month my 330ci blew the hg. I crank up my car one cold morning and went inside for coffee ,after returning back about 10 min I notice the needle was in the redzone. I almost shitted in my pants . I shut off the engine quickly and proceed to the hood . The top hose was bloated up and obviously the bottom hose was cold . I waited and crank her up about 30 min later same old crap . The fan didn't turn on obviously the cold lower radiator hose . A month later im getting real high pressure in the radiator as soon as I crank up the engine . Then the radiator will get exhaust fume out of the expansion tank everytime I rev up. I then check the obc temp of the car and it read 124 degree. I thought about it is that farenhiegh or celcius then it was too late . The needle is no where acurate you can be around 10 degree or maybe 15 and it will still show almost no movement in the needle until it's starting to get dangerous . Should I do a HG job or throw in a used m54b30 ... I have done maybe more than 30 engine swap before but never BMW . I don't want to dump the car too . How hard is this replacement ...

[Drana16]

1255 sola


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[legoman67]

used M54. The block is probably warped, and there is a good chance the threads for the head bolts will pull out when you try to torque the head back on.

[asianvenom]

Do the head gasket. The pita part of the job for me was remove/install the exhaust manifold bolts, everything else was straight forward.

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[magnetchief]

It’s all a pain in the ass.
Sounds like the head has cracked.
If so you could get away with a head swap. But honestly that may drag up other issues like pulled threads.
Swapping my the whole engine for a known good one is doable. May even be easier than replacing just the head.




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[Mless5]

"I then check the obc temp of the car and it read 124 degree" - FYI that is ambient air temperature and it reads + 124F when the sensor in not plugged in.

[randy72877]

I would remove the valve cover and set the engine at tdc position (to access head bolts) then loosen all of the head bolts and re torque following the steps and sequence. If the threads hold I would fix it. If not, you have to decide. It will need time serts in the block which will add significant cost to the repairs. You never know what you are going to get with a used engine. You could swap it and end up with an engine that is worse than yours. Most junkyards don't run them long enough to find a head gasket problem. They just start it briefly and if it doesn't knock, they will sell it. If you do repair your engine I would recommend taking the head to a machine shop to have it professionally checked for cracking and warpage at the minimum.

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[legoman67]

You never know what you are going to get with a used engine. You could swap it and end up with an engine that is worse than yours. Most junkyards don't run them long enough to find a head gasket problem.

Its fairly easy to see a head gasket problem engine. The coolant is normally black, or the oil is milkshake. Also most cars at junkyards were running when they crashed, so there is a good chance that it has no serious issues.

Junkyards also usually warranty used engines for 90 days, so if there is an issue you are only out your time if you DIY.