valve seat problem

olivajeep · Post by **olivajeep** » Mon Feb 05, 2007 12:49 pm

can someone tell me why. i just had a secound valve seat drop no damage other than the valve seat and valve the first time the head was tested for cracks and then fixed (good job looked like new with all new parts) the same valve seat droped again (#3cyl exh) the head shop said thay will fix it no problem. but why is this happening and is ther anything i can have done to prevent this. i know that the heads are semi prone to this just because the two materials just dont mi x but what can be done to prevent this?
74 2.ol about 15k on it other then this no problems.

Bleyseng · Post by **Bleyseng** » Mon Feb 05, 2007 2:10 pm

The OEM seat material and the Aluminum head expands are vastly different rates plus at about 425F the seats will drop out due to poor tolerances at install. Or there are cracks that need to be fixed as the exhaust seats usually aren't the problem.

The solution is to use Adrain at HeadflowMasters or Len at HAM to do your heads as they use different seats and very tight tolerances so the seats stay in.

The other thing is if the heads are high mileage the aluminum gets soft under the seats so they are junk.....

olivajeep · Post by **olivajeep** » Mon Feb 05, 2007 2:53 pm

the car only has 46000 original miles is it posible i have a bad casting

Bleyseng · Post by **Bleyseng** » Tue Feb 06, 2007 12:12 pm

no, but it could be running really hot Cylinder Head temps that don't show up in the oil temps for quite awhile.

Or poor repairs on the heads by the PO or this head shop.

Proper up to date installation of the valve seats is done by a few shops only. Most VW head repair shops don't know crap about the Type4/Porsche heads! Use only the shops that KNOW.

olivajeep · Post by **olivajeep** » Tue Feb 06, 2007 12:43 pm

what are some good places to have the heads fixed right im in phoenix az

Bleyseng · Post by **Bleyseng** » Thu Feb 08, 2007 11:58 am

None that I know of.

Len at Hoffman Auto Machine in GA-

http://www.haminc.biz

ship them to him, call first

or Headflow Masters in calif

olivajeep · Post by **olivajeep** » Thu Feb 08, 2007 12:50 pm

i think i will try the place in cali thanks for all the info again. this forum is one of the best places i have found for good solid info.

raygreenwood · Post by **raygreenwood** » Thu Feb 08, 2007 8:08 pm

Do some research on this. There have been...like thousands of words written on this. There were some issues with the "middle years" on type 4 cylinder heads pursuent to the interference fit of the valve seats in the heads. No one is really quite sure...but the problem was rampent. Mostly in busses (read that as heavy and running hot) and 914's..(read that as run hard). When overheated repeatedly (which many times came from poorly adjusted fuel injection)....the seats become loose.Part of this can be because after a while the aluminum....repeatedly overheated...looses its elastic memory.
Someone who is skilled....in installing valve seats with a greater than factory inteference fit must work on the heads and install new seats. Not expensive...and part of a general and common rebuild for type 4. But..if you go to the run of the mill or average shop....you may be sorry. Len hoffman....and headflowmaters (two different companies ....do a search)...are the best and most practiced. If they are not type 4 head specialists that you go to.....be ready to FURNISH the specs and expertise....or else ....beware. Ray

olivajeep · Post by **olivajeep** » Mon Feb 12, 2007 12:43 pm

thx ray i will look into having this done