Cracked Head

autowerks

autowerks

Well-Known Member
Site Donor
Messages
561
Reaction score
82
Location
Dallas, Texas
Hello all, 1971 2800CS, I think my engine's head is cracked
loosing a bit antifreeze and a lot of white smoke out of tail pipe when I first start the car when the engine is cold, no water in the oil though.
If anyone has had these symptoms/
Any help with what type head will work and the cam types I can install will be appreciated,
Thanks in advance Joe
 
That happened to my 2800CS about 10 years ago. The head was not cracked but I found a small hole leaking coolant into an exhaust port. Apparently there was porosity or some kind of defect in the head in that area and after many years of use it broke through. A little corrosion may have contributed. I put on a new head but have kept the old one thinking I would eventually get it repaired. It was a really good performing head, much better than the one I have now. Anybody know of a good place to get an aluminum head welded?
 
Yes, my original head was cracked at two exhaust valves when I bought Athena. Sourced a 1986 head from Memphis Motorsports in 2011 and have been fine ever since.

-2.jpg
-3.jpg
 
I have a perfect head from a 3.0cs should you wish to replace rather than weld. It is date stamped '84 from memory so the car it was fitted to clearly had it replaced as that car was a 1972. All components on it were still original. It is for carburation with the mechanical fuel pump hole and came off the car I parted out... in other words, it is not from a fuel injected later car :)
 
The easiest way to crack a head is to put cold water into a hot or overheating engine, if you ever HAVE to put cold water into a hot engine have it running, Your head may be cracked or it could be corrosion around the head gasket / water passage, usually at the rear of the head,

Any head will work if you have flat top pistons, if not then you must match the piano shape of the piston to the lumps in the combustion chamber,

Re. a head with a porous port, the problem with TIG welding it is that you need good access to the hole, if it is inside the port it cannot be TIG welded, I once "welded" a porous hole in an inlet port using technoweld or lumiweld but it was a major problem getting the head up to the required temperature, it worked though...... Pat
 
pat cooks said:
The easiest way to crack a head is to put cold water into a hot or overheating engine, if you ever HAVE to put cold water into a hot engine have it running, Your head may be cracked or it could be corrosion around the head gasket / water passage, usually at the rear of the head
Click to expand...

Hmm you know I didn’t think of that. I took my jeep in for a coolant flush and it came back with a head gasket / head issue. It’s a cast iron head but the techs and the service writer (owner) were incompetent. Of course they shut down about a month later...
 
Heads, and wheels can be TIG welded successfully BUT if you don't want them to crack again they should be pre heated ideally in an oven, welded, then placed back into the oven and brought down to room temp over as long a period as possible, like 24 hours, or packed in insulation in a box to cool down VERY slowly, IMHO, Pat
 
autowerks said:
Hello all, 1971 2800CS, I think my engine's head is cracked
loosing a bit antifreeze and a lot of white smoke out of tail pipe when I first start the car when the engine is cold, no water in the oil though.
If anyone has had these symptoms/
Any help with what type head will work and the cam types I can install will be appreciated,
Thanks in advance Joe
Click to expand...

That describes exactly the issue that I had. Replacing the cylinder head remedy all the problems.


Sent from my iPhone using Tapatalk
 
I am running triple Webers with electric fuel pump, will call Sir. Don to see what he suggests but I would like to get a different head since mine is stamped 1970 not being the best BMW ever made
 
Thanks Scott, I saw your post and new I have the same Issue, the car temp went up to about 1 o'clock one day in traffic and I installed a 16" Aux fan but a little too late
 
You must log in or register to reply here.
Back
Top