Looks like my HGs are going again on my 98 2.5 dohc. But...the MLS gaskets (i replaced them last year) are made of steel...how could this be? I havent overheated the car ever.

 

Getting what smells like exhaust in the overflow bottle. Bottle is getting full and rad is getting empty. Assuming its an internal failure between exhaust and coolant passages. New rad cap...no coolant out the tailpipe or on the ground and no visible leaks. Using subaru coolant and conditioner too.

 

Has anyone else had the replacement MLS gaskets fail on them?

Did you have the heads decked/resurfaced and prep the block face as well? IIRC, the OEM MLS gaskets require VERY specific surface prep in order to ensure proper sealing.

 

Actually, it was the OE metal MLS that failed in the 25D. They claimed to have FINALLY fixed the OE design flaw and materials, but after 2 sets of the 'final' design failing, I've given up on FHI non-turbo head gaskets.

 

Switching to Fel-Pro's LaserWeld or the composite style gaskets, I've never had a problem on the 10+ 25D/222/253/251 I've done in the past years. Some have 100k+ since the gasket swap.

Edited November 25, 201510 yr by 86 Wonder Wedge

Sigh...no. I tried to shortcut the downtime by just cleaning the surfaces myself...worked great on my old ea82s but i guess its truly not good enough for the 2.5d.

 

As per your recommendation, I'll try the composite/laser weld gaskets you speak of now AND get the heads decked.

Honestly, I've never needed to deck the heads with Fel-Pros. If you have a good straightedge, check for warping, of course, but then scuff with the red scotch-brite pads, brake clean and call it a day. That's how I've done ALL the non-FHI gaskets since. The Fel-Pros are not nearly as picky as the OE.

Interesting. I used the old felpro petmatorques on my ea82s too...and none have leaked. Hmph.

 

I did check them with my straight edge and they seemed good with the feeler gauges.

 

Thanks for your advice. One last question for you...do you recommend new head bolts too?

AHHHHHHHH!!!!! DO NOT just scuff up an aluminum head with red scotchbright. That stuff is sharp and will cause somewhat deep grooves (as far as a gasket is concerned), you'll also end up making low spots because nobody is perfect. The 2.2 and ea8x engines are a bit more tolerant to doing things improperly, but not the 2.5. GD has a very good post on DIY head surfacing. As you know, not doing it right means doing it again. The only time I had a subaru headgasket fail on me a second time was because I used felpro MLS gaskets. The coating came off between the combustion chamber and the coolant passages, looked like a stock 25D headgasket failure.

 

Subaru heads almost never warp, I've seen them overheated to seizure and the heads were flat. They're so small you really don't have to worry about it.

Edited November 25, 201510 yr by 987687

Thanks! I don't know how many times ive followed a GD writeup!

 

Im gonna make that rig for sure.

Fel pro gaskets on a 2.5 are a no no. Use oem STi headgaskets or 6 star, and as said, prep Isa huge part of the job, and then following the proper torque sequence.

AHHHHHHHH!!!!! DO NOT just scuff up an aluminum head with red scotchbright. That stuff is sharp and will cause somewhat deep grooves (as far as a gasket is concerned), you'll also end up making low spots because nobody is perfect. The 2.2 and ea8x engines are a bit more tolerant to doing things improperly, but not the 2.5. GD has a very good post on DIY head surfacing. As you know, not doing it right means doing it again. The only time I had a subaru headgasket fail on me a second time was because I used felpro MLS gaskets. The coating came off between the combustion chamber and the coolant passages, looked like a stock 25D headgasket failure.

 

Subaru heads almost never warp, I've seen them overheated to seizure and the heads were flat. They're so small you really don't have to worry about it.

 

I have to respectfully disagree with you on the warping.   Subaru heads are notorious for warping, and the tolerances have gotten to ridiculously low limits.  The EJ25 DOHC heads had very little in the way of coolant passages and therefore, warped very easily.  It is critical that both the heads and block need to be absolutely flat for any gaskets to adhere properly.

 

Emily

Did you have the heads decked/resurfaced and prep the block face as well? IIRC, the OEM MLS gaskets require VERY specific surface prep in order to ensure proper sealing.

 

Actually, it was the OE metal MLS that failed in the 25D. They claimed to have FINALLY fixed the OE design flaw and materials, but after 2 sets of the 'final' design failing, I've given up on FHI non-turbo head gaskets.

 

Switching to Fel-Pro's LaserWeld or the composite style gaskets, I've never had a problem on the 10+ 25D/222/253/251 I've done in the past years. Some have 100k+ since the gasket swap.

I've wondered about this. Are you saying you've used the composite style gaskets (From 90-98 SOHC EJ22) on the DOHC 2.5 motors? Is there cutting involved?

 

Thought about it a few times since the 2.2 heads can go on the 2.5 block and the MLS gaskets are such trouble in those years. Why not put that more forgiving a squishy gasket in there.

Bratman...thats what i thought too...which is why i went with MLS last time. But they appear to have failed rather quickly and im up for whatever works best.

 

Decking the heads for sure, maybe new bolts, but now i dunno about the gasket...lots of different opinions here.

I think maybe the prep was where they went wrong last time. No need for new bolts. I personally would use the 6 start gaskets. I know a mechanic that has been using them for years, with no return failures.

Thanks bratman. I see them on ebay. Ill give them a shot.