Check for stripped headbolts before head removal?

[auaq]

Yes, I was later looking at the cooling system of the M54 and it did seem different according to the flow.

[m735is]

I will definetly check the block when the head is removed. Just to save up for the Timesert stuff and head gasket stuff before I remove the head. Then I can save up for the vanos jigs.

[tonyisok]

My attempt at testing cylinder head bolts liked like this: Initially set torque wrench to 30 ft/lbs and 13/14 bolts held. Increased torque to 40-ft/lbs and the same 13/14 bolts continued to hold. The single bolt that was loose was the #1 bolt (EA). I'm thinking I will need at least one time sert. My question is should I proceed with replacing head gasket?

[djb2]

The next step is to do a leak-down test. Note which cylinders are sealed, leak slightly (probably the valve seats -- a quick lap might help) and which have massive leaks.

Then take off the head and see how warped it is. It's easy to do with a metal straight-edge. For the first round you can even skip a feeler gauge and use paper to locate the high and low spot.
If the head isn't too warped, check the cam carrier ledge. If it's not flat, the head will need to be baked to relieve stress and perhaps even bent (put under pressure while being baked) to flatten it. Depending on your local machine shop cost, this might push the cost over the edge to buying a used head. At that point a good used engine might be a better choice.

[effduration]

This whole business of testing threads in an BMW aluminum block (you have the M52TU engine, but M54 is same) is crazy, an ineffective test and a waste of time. The real test is whether the head is cracked or too far warped that it can't be machined flat with 12 thousandths of an inch, which is the maximum amount that can be removed, and which would require the thicker head gasket.

I recently successfully replaced a head gasket in my M52TU engine for the first time. I suggest you take the head off and take it to a machine shop familiar with BMW aluminum heads. I time-serted all the the threads in the block. It is quite easy. I bought the Time sert 1090 kit new and sold it on ebay (used) at a $100 discount

[djb2]

I wouldn't say that it is ineffective.

It will tell you if you need to repair the threads. If your head is really warped, that might tips the scales to buying a good used engine. If all of the threads are good, it makes it easier to decide that the engine is worth saving.

[effduration]

Time-serting all the threads in an M52TU/M54 aluminum block is really an easy and relatively cheap DIY with the proper tools that can be borrowed/rented. It should be a standard part of the head gasket procedure on these engines whether or not any of the threads have stripped, as it is with other engines (GM Northstar). If the engine has overheated even a little bit, the chance that one or more of the aluminum threads will strip on re-torqueing is 50/50 and to find that out near the end of a head gasket job is a real bummer.

Much more effort, complexity and expense is involved in the inspection, machining, and re-installation of the head with associated re-timing of the dual vanos.

The decision to replace an overheated engine with a good, used engine can often be the sensible, economic move, but we may soon find ourselves with reduced supply of good used M52TU and M54 engines. Since time-serting engine blocks is really quite easy, I wouldn't let the issue of stripped threads factor into the decision.

[sorter]

I agree to do the timeserts on all the buggers, I was testing them all upon removal, had the head skimmed, new bolts, new gasket, all torqued down fine to 40Nm but on the first 90 degree two pulled threads - I need new set of head bolts, most likely (surely really, but still hoping) new head gasket. Again. I would understand it if I wouldn't test them, but did and all of them torqued fine, no odd signals on undoing the bolts for the first time... Just pure annoyance. Not sure if I want to go ahead with it now anyway, lost interest in the bugger, as it wasn't far off with removing / installation of the exhaust manifold studs and they only torque down to 10Nm. Not impressed with the design at all.