DIY: Valve and 2.5L Headgasket Repair

[subaruVWnut]

After diagnosing no compression on #3, a leakdown test shows problem with exhaust valves.

 

Engine is out.

 

Removal of left head reveals a cracked exhaust valve.

 

So now some decisions and...so I have some questions.

 

I decided to remove both heads and (at least) replace both headgaskets along with the broken valve......

 

Here's my dilemma.... The original compression test showed even compression ....but not very high compression...around 125-130 on the other three cylinders. So I had planned to do complete head reconditioning and valve job to both heads, but adding up all the machine shop and parts cost is getting pretty expensive

 

So.....????

 

1. Should we do a valve job on both heads...to improve compression or just fix the one cracked valve.

 

2. Should valve guides be replaced? They're expensive.

 

3. Is it OK to re-use the head bolts? They're also expensive.

 

 

Is there a standard list of recommended tips/ cautions and parts list to replace during valve/head gasket repair?

 

Warren C

[Phillip]

To determine how far to go, I'd ask myself how much longer I planned to keep the car, and what kind of shape the rest of it is in. If the car is pretty well used up and you don't care how much longer it will last, I'd just fix the bad valve and when something else fails, junk the car. If I planned on keeping it more than another 10,000 miles, I'd have both heads reconditioned. You've already done the hard work - the engine is out and the heads are comming off; no sense in doing it again later in my opinion. Regarding the valve guides, the machine shop cannot grind the seats unless the valve guides are within spec. Rather than replace the guides, you could have them knurled (expanded with a knurling tool then reamed to size). While it's not as good as replacing the guides, I've had good experience with many OHV engines - your machine shop can advise you best on knurling and on your cylinder head reconditioning questions. If the guides are badly worn, the valve stems may also be worn. Perhaps a used set of heads from a wrecking yard may be a cheaper option (have them inspected by a qualified machinest before installing them). Regarding reusing head-bolts, you'll likely get a variety of opinions. I typically reuse them, and have never had a failure. Bottom line, cheap fixes are generally cheap only in the short-run. That said, I've made lots of cheap fixes when I had little money - not many of those fixes worked out in the long-run. Let us know what you decide to do.

After diagnosing no compression on #3, a leakdown test shows problem with exhaust valves.

 

Engine is out.

 

Removal of left head reveals a cracked exhaust valve.

 

So now some decisions and...so I have some questions.

 

I decided to remove both heads and (at least) replace both headgaskets along with the broken valve......

 

Here's my dilemma.... The original compression test showed even compression ....but not very high compression...around 125-130 on the other three cylinders. So I had planned to do complete head reconditioning and valve job to both heads, but adding up all the machine shop and parts cost is getting pretty expensive

 

So.....????

 

1. Should we do a valve job on both heads...to improve compression or just fix the one cracked valve.

 

2. Should valve guides be replaced? They're expensive.

 

3. Is it OK to re-use the head bolts? They're also expensive.

 

 

Is there a standard list of recommended tips/ cautions and parts list to replace during valve/head gasket repair?

 

Warren C

[1 Lucky Texan]

You might consider speaking to Emily at CCR. I dunno it they have just heads or not but they may be able to advise you at least.

 

http://www.ccrengines.com/

 

no connection, interest blah,blah

[idosubaru]

what are the stock specs for compression? a good way to test compression is to remove all the spark plugs, remove the intake, prop the throttle body open and no fuel pressure and a good cranking starter/battery and all this on a warm motor. if you don't, your compression readings will read a little lower than stock. i find propping the throttle open, testing when warm and removing all the spark plugs will make a noticeable difference in compression readings. but i'm not familiar with the 2.5. also - verify the compression tester is accurate before toasting the motor.