M42 Overheated...No start (with video)

[kwill22]

Would've never happened if the M42 was running. Lol

Get well soon

[Vivek]

Any updates on this OP?? Did you replace t-stat? Did it help?

No real updates yet. Basically waiting for an engine from Steven on this forum. I also recently hurt myself in a motorcycle accident so working on my car just hasn't been happening with me being in bed for the past week.

[kwill22]

Make it happen

[chodedub]

I'm having the same issue with my 91 318 m42, po overheated the engine felt it bog passing a semi then pulled over shut it down. Did a dry compression test with similar results as u then a dry one again with similar results. So I now have a winter project, rebuilding the motor as does my body shop owner friend the body. If all goes well I will be on the road this spring early summer, then next winter rebuild again for BOOST!!!

[kkamakasi]

Any updates on this OP?? Did you replace t-stat? Did it help?

[kwill22]

100 bucks is high for just resurfacing. Is that Cali markup?

If you swap engines. Still search for a head and build an M42 turbo!!!!

[bmwman91]

The passenger side radiator hose is going to feel considerably cooler than the driver's side one because it is the outlet from the radiator...it is the coolant that has been cooled off.

[Vivek]

the cheapest I could do a hg and top end job with new valve seats gaskets ect was around 400 some bucks.

kinda a sucky situation. GL OP

Thanks. I can get a new engine and tranny for 350. I'll probably just end up doing that, just want to confirm that the bubbles in the radiator are combustion gases, although everything clearly points to that being the case. Also, do you know why the hose on the exhaust side of the thermostat housing would be cold even though the temp gauge is reading halfway or higher? I've also wanted to pull my engine out for a while to clean up my bay and my trans leaks (along with my engine from the oil filter housing and some other places). Oh well, it'll be a good time to get some stuff done and clean up my bay, also swap my steering rack with the e36 one I've been putting off for a while.

[Dj Buttchug]

the cheapest I could do a hg and top end job with new valve seats gaskets ect was around 400 some bucks.

kinda a sucky situation. GL OP

[roguetoaster]

In all likelihood, if the heads cracked, I may just swap in a new engine. A new head would be 1-200, if I can find one. Then probably a hundred at a machine shop to get it resurfaced, and easily 200 for the headgasket and other seals and gaskets for it. At that point I'd be into it more than the price of a new m42. And I can source one from a friend locally who's swapping his so I know the history and mileage on the engine, and I've driven the car and it's always felt stronger than my m42.

If it's simply a matter of cost then by all means go for a new used engine, but if you can afford it a refreshed M42 top end/timing components/water pump should be reliable for years. Anyway, with some thought before hand you can easily take the M42 out and replace it in under 2.5 hours. Whereas you might be that long just getting the exhaust manifold off of the damaged cylinder head!

[Vivek]

In all likelihood, if the heads cracked, I may just swap in a new engine. A new head would be 1-200, if I can find one. Then probably a hundred at a machine shop to get it resurfaced, and easily 200 for the headgasket and other seals and gaskets for it. At that point I'd be into it more than the price of a new m42. And I can source one from a friend locally who's swapping his so I know the history and mileage on the engine, and I've driven the car and it's always felt stronger than my m42.

[LoneWolf]

Sometimes they can be hard to find, and shipping is often a 25% price increase over base cost. But I do agree with your sentiment, crack sealer is not the right solution in this case.

Replace the stem seals when you get it resurfaced (along with the timing cover) if you get a new to you cylinder head!

This.

M42 stuff isn't as common and cheap as it once was. Still cheaper than most other engines I suppose.

[roguetoaster]

Just replace the head with a known good one. Its not like M42 heads are really expensive!

Sometimes they can be hard to find, and shipping is often a 25% price increase over base cost. But I do agree with your sentiment, crack sealer is not the right solution in this case.

Replace the stem seals when you get it resurfaced (along with the timing cover) if you get a new to you cylinder head!

[wazzu70]

Just replace the head with a known good one. Its not like M42 heads are really expensive!

[DesertBMW]

I suppose I could try that block sealer...wouldn't have much to lose.

With the KW you must drain all of the water from the block, the block drain is located on passenger side rear block, 19mm bolt. Remove spark plugs let it all dry for at least 24hrs, if you live in colder weather, allow 2 days.