Back in April, my 99 OBW EJ25D (2.5 DOHC) with 150k overheated on a trip. It was low on coolant and I topped it off and drove for a while. It overheated on another trip. I was afraid that I was starting to develop the HG problem. It progressed to the point that i was adding 1/2 liter of coolant per day and the car wasn't reliable. Last week it threw a code, started running poorly, and was slow to start. I've got a temporary car and am now planning on doing my first HG job.

 

 

1. I read that the factory HG develops this problem at about this age. Will an OEM replacement not develop the same problem? Have they fixed it?
   
2. I recently read in a engine rebuilding book that copper HGs are one of the better types because they conform to the imperfections on the mating surfaces. Has anybody used copper performance gaskets? Do you think they're better/more reliable than OEM? I just want the car for daily driving.
   

Search here. Most of your questions should be answered by doing some reading.

 

Look for endwrench links mostly.

 

Use OEM head gaskets.

 

Have the heads checked/surfaced sense you abused it soo long before deciding to fix it.

Replace with Subaru headgaskets. Have the heads machined, read all the posts on here about how to do it. Call the local dealer and find out who does their machine shop work.

Thanks for the responses. I found some posts that really made me feel less apprehensive about the whole deal. I'm going with the OEM parts from 1stsubaru. Wish me luck!

OE gaskets have changed part numbers a few times since your car was new. This indicates a change in vendor and/or a design change of the gasket itself. Go OE for all parts on this and mill the heads. And always follow the proper torque sequence for the head bolts.

Thanks. Will do. Seeing those who have successfully resurrected their motors from the grave gives me hope! I'm going to replace the following while I'm at it:

 

• Head gaskets
  
• Water pump
  
• Timing belt
  
• Idler pulleys
  
• hoses
  
• valve cover seals
  

Thanks. Will do. Seeing those who have successfully resurrected their motors from the grave gives me hope! I'm going to replace the following while I'm at it:

 

• Head gaskets
  
• Water pump
  
• Timing belt
  
• Idler pulleys
  
• hoses
  
• valve cover seals
  

 

You are doing all the right things in replacing the above parts. Good Luck!

Reseal the oil pump and replace cam shaft seals too while you're at it. Or at least any of those that appear "wet", meaning those are likely to leak.

 

And PCV and thermostat too - that's a Subaru only part by the way, the aftermarkets are super cheezy, they look like toys for your toddler compared to the Subaru ones.

Reseal the oil pump and replace cam shaft seals too while you're at it. Or at least any of those that appear "wet", meaning those are likely to leak.

 

And PCV and thermostat too - that's a Subaru only part by the way, the aftermarkets are super cheezy, they look like toys for your toddler compared to the Subaru ones.

 

Yes. Yes. And yes.

Crank seal, cam seals, t-stat & gasket, water pump by-pass hose... OE way better on all accounts.

This may be a 'given', but also suggest checking the valve clearance while you got it out.

This may be a 'given', but also suggest checking the valve clearance while you got it out.

A "must" anytime the cams are going to be off this engine... Or anytime the adjusters are staring right at you on others.

I was under the impression that these engines have hydrolic valve adjusters that auto adjust the clearances. The FSM says to use shims. Do these not use HLAs? Here's what the FSM shows:

 

some have hydraulic valve lash adjusters and some do not. if someone knows, please differentiate for us when that change occurred? only 96's have HLA's...??

[...] only 96's have HLA's...??

That's right, '96 was the only year that the 2.5L had HLAs. It was also the last year for HLAs in the 2.2L. Unlike 2.2's with screws and locknuts on the rockers, the '97-99 DOHC 2.5 requires selecting shims for clearance adjustment.

Unlike 2.2's with screws and locknuts on the rockers, the '97-99 DOHC 2.5 requires selecting shims for clearance adjustment.

 

That sucks. I like the screws and locknuts. How expensive are shims? How hard are they to get?