Subaru Impreza STI Heads Gaskets

[thecube]

So, my 06 STI has done its head gaskets for the 3rd time (slight bubbling into expansion tank). First time the head gaskets were done at 40,000 using Subaru parts, again at 70,000 (then had heads skimmed, ARP head studs, cosworth gaskets, new clutch blah blah blah, pricey!) and now done it again after only another 14,000 miles. It's completely standard and always has been, so seems pretty weird. It doesn't even get driven particular hard - I have mechanical sympathy :-) (even more so given the history). So I don't understand it. Or what to do with it. In every other respect it's in great condition and has been really well looked after by me (I'm the only owner from new).

So after advice really. Not sure I want to try again. No idea what it's worth in its current state. So I'm any suggestions either on where to sell it and what it's worth with the HG problem, or what to do differently on a rebuild.

[stevieturbo]

Assuming the work has been done correctly and to a sensible standard, then it should not be happening.

Whilst newer blocks are stronger than old open decks, busted liners are a relatively common problem with the 2.5's

Well...common in that they do happen, when it should never happen.

So you're saying the HG's have blown...when rebuilt, was it visually obvious where the gaskets had blown ? I presume whoever rebuilt it did take not of this ?
It should be pretty obvious where the blow occurred, so if there are to visual signs, a liner could well be suspect.

[thecube]

Thanks for the reply. I did talk it through when it was done - the heads and liners were inspected although I didn't actually go and eyeball them myself, heads I think he said had some pitting because of the leak and hence were skimmed to clean them up and ensure a they had a good surface for the gasket.

If it's down to the liner, what normally happens? A small crack down from the gasket surface? Any suggestions on what to do/ likely cost? Any good places doing exchange engines?

[thecube]

Thinking about it, a cracked liner wouldn't last 14,000 miles and then fail would it?

[crossy67]

Being liners I take it they have some form of a seal at the bottom? Is it not possible someone has been concentrating all their efforts on the wrong end?

[stevieturbo]

thecube said:

Thanks for the reply. I did talk it through when it was done - the heads and liners were inspected although I didn't actually go and eyeball them myself, heads I think he said had some pitting because of the leak and hence were skimmed to clean them up and ensure a they had a good surface for the gasket.

If it's down to the liner, what normally happens? A small crack down from the gasket surface? Any suggestions on what to do/ likely cost? Any good places doing exchange engines?

The chances of the heads being "pitted" are almost none, but if the gaskets had been leaking, again this would have been clearly visible as to where. Even on engines that show minimal symptoms, when the heads are removed, it is very visible as to where the head gaskets are leaking. Most usually on the exhaust side of the chamber.
Skimming the heads is routine mainly to ensure they are flat and surface is good. If there was actual pitting on the head face, you have other issues.

Also, when the heads are skimmed, the finish must be super smooth. No rough cuts at all as some machine shops will do.

Likewise he should have inspected the top of the block faces to ensure these are perfectly flat and also cleaned them perfectly clean.

I've seen liners damaged at the top where they meet the alloy casting, I've seen them completely burst or a simple hairline crack. So really anything can happen
But yes you would expect symptoms before 14k assuming a varied style of driving throughout that time.

Really without seeing it, impossible to say. And work standards vary more than just a little around the country I'm sure.
Hell....it could even be as simple as the head studs were not installed and torqued correctly. This would have been apparent on stripdown to a degree, and again the visual signs of how the gaskets had blown.

If it is a liner, really you need to source another block. As for "re-con" engines....havent a clue. Recon means many things to many sellers
Unless you had 100% faith and trust in the seller...I wouldnt go near one.
You'd be better having your own parts rebuilt by a reputable and trustworthy shop.

Sourcing a used engine....possible, but given the 2.5's do have known HG and other issues....that too can be a risk.

Unfortunately there is no easy or cheap fix here. And without proper diagnosis of cause...hard to give advice as to where to go.
Whoever was carrying out the work should be in the best position to give this advice as they've seen everything first hand.
If they arent able to diagnose with a fair degree of certainty...that's a little concerning too.

[thecube]

Thanks for taking the time to write all that stevieturbo. In the end I found someone who was prepared to buy it in its current state so I let it go.

With everything I've read about the 2.5 engine on head gaskets plus my own experience, plus the ringland failures, I don't think I would ever risk owning another 2.5 Impreza.

I don't think I'll continue with Subaru after this (my 3rd Impreza from new, but only this one was a 2.5) unless I can find a good low mileage JDM 2.0l Impreza. So any recommendations on JDM importers are welcome . . .

[stevieturbo]

2.5's just arent great.

That isnt to say good 2.5 engines cannot be built though, or 2.35 etc

Probably the best all rounder was the 06 JDM Hawk Spec something or other that was a 2.0 twin scroll etc

Litchfield is probably one of the bigger names for imports.