1990 535i block cracked?

[lilcallaway]

I've just bought a decent car that supposedly has a cracked block (as I was told). Can it be a misdiagnosis? Wouldn't the head crack way before the block? I know I need to check the over heating parts as per bmwe34.com.
I'll be taking a thorough analysis Tuesday evening. Let me know if there's anything I need to particularly look at.
Lastly, how hard is it to do a block swap?
Thanx in advance....

 

[Kirby]

The block can certainly crack without the head failing. Swapping the block is basically doing a complete engine change. Typically you buy a rebuilt short block, remove all the components that are good/reusable from the old block, buy new parts where needed, and put them on the new block.

 

[lilcallaway]

Thanx Kirby!
Does this block have freeze plugs that could've gone bad? (Looks like I won't be picking it up till Friday to find out where it's leaking.)
And there is still a chance the head could be warped, correct?

 

[jrt67ss350]

Yes, it does have freeze plugs, and yes, the head could be warped.

 

[Kirby]

Keep in mind that the block or head can be cracked, but you may or may not be able to actually see the crack. Cracks usually open up under operating heat and pressure. Unless you can completely rule out a crack, such as a finding a bad freeze plug or blown head gasket, you should consider having the head and block magnafluxed and resurfaced if you are going to reuse them.

If you knew the exact conditions that lead up to the failure, it might not be necessary, but since you are buying it like this, who knows what the true story is...

 

[lilcallaway]

Thanx for all the replies!

Kirby....I'll do a search, but what exactly is magnafluxed? Should I do that anyway if I end up with another block?

I'll try to make a long story short. The lady who I purchased the car from basically said that it had ran hot, took it in, and had the thermostat replaced. Car got hot again, took it in, and apparently the stat was installed the wrong way. Ran fine a while, got hot again, and we are where we are today. It 'looks' as if the fan clutch has been changed. The water pump has been changed at least twice according to the paperwork. (BTW, what's the lifespan on a water pump?) I believe that I have practically all the paperwork for repair history. The fan clutch and stat was changed in June 02' and the stat was changed again Sept 04'.
I never saw where the head gasket was changed, but there is a recommendation for it and the timing cover gasket to be changed in Nov 98'.
Any comments?

 

[Kirby]

From what I have seen in various posts, when you have overheating problems on these engines, it can be a real pain trying to find the cause and solve it. Water pumps should last 100K miles or more. There was an issue with some water pumps that had plastic blades that failed early, I know this was a problem on the 3 series in the 90's, I assume the 6 cylinder 5 series also had the problem, but I don't know that for a fact. What year is your car?

The 3 series requires a specific bleeding procedure to remove air from the system, I'll guess that the 5 is similar. If it is not bled properly, overheating can occur. I guess I would start by doing a flush and coolant change, make sure that all the air is bled out, and see what happens.

If you loose coolant level quickly and see no leaks, you have a cracked block or head, or blown head gasket. Another clue is steam and a sweet coolant smell in the exhaust, or water in the oil. Look for these clues. If these do not show up, you probably do not have a cracked block or head gasket problem.

I have read that another cause of overheating can be related to the heater divert valve, but I have no specific experience with this, and don't know if that applies to your model.