blown subie head gasket

Vincent Keene · **Posted:** Thu Nov 11, 2010 4:04 pm

Aaron Buckley wrote:

For most cars I've worked on, re-using head bolts is like re-using a condom... - AB

Most head bolts are torque-to-yield, which means no re-use.

Vincent Keene · **Posted:** Thu Nov 11, 2010 4:07 pm

RodneyWright wrote:

It's my understanding that head gaskets are common failure points on these engines. But that does bring up a good point. Do I have to get these heads redecked or can I just put it back on. I really don't want to dump a ton of bucks into this car.

Why would the gasket just fail? Either the engine was overheated and warped the head, or the engine was overheated and stretched the head bolts.

Theoretically speaking, two perfectly flat surfaces can seal with no gasket at all, which is why gaskets are used in the first place.

Aaron Buckley · **Posted:** Thu Nov 11, 2010 4:10 pm

Vincent Keene wrote:

Why would the gasket just fail? Either the engine was overheated and warped the head, or the engine was overheated and stretched the head bolts.

Theoretically speaking, two perfectly flat surfaces can seal with no gasket at all, which is why gaskets are used in the first place.

In the boxer world, these engines have a gasket that seems to degrade over time, causing the failure. Similar to the original M42 engine profile gasket in the BMW 318i/s from '91. - AB

RodneyWright · **Posted:** Thu Nov 11, 2010 4:12 pm

Vincent Keene wrote:

RodneyWright wrote:

It's my understanding that head gaskets are common failure points on these engines. But that does bring up a good point. Do I have to get these heads redecked or can I just put it back on. I really don't want to dump a ton of bucks into this car.

Why would the gasket just fail? Either the engine was overheated and warped the head, or the engine was overheated and stretched the head bolts.

Theoretically speaking, two perfectly flat surfaces can seal with no gasket at all, which is why gaskets are used in the first place.

I'll have to let someone else speak to why these are failure points on the car. I'm still a noob on these cars. The car did not run hot as far as I know.

RodneyWright · **Posted:** Thu Nov 11, 2010 4:13 pm

Vincent Keene wrote:

Aaron Buckley wrote:

For most cars I've worked on, re-using head bolts is like re-using a condom... - AB

Most head bolts are torque-to-yield, which means no re-use.

OK, looks like I have plunk some bucks down on head bolts..... Anyone know of good source to buy these?

Vincent Keene · **Posted:** Thu Nov 11, 2010 4:23 pm

Most of the performance world swear by ARP, but they ain't cheap.

JamesShort · **Posted:** Thu Nov 11, 2010 4:28 pm

You can't pull the engine and tranny out as one unit if I'm not mistaken...nor would I recommend it if you could. Just take the radiator out and separate the engine and tranny and yank the engine out...it's pretty light.

RodneyWright · **Posted:** Thu Nov 11, 2010 4:30 pm

JamesShort wrote:

You can't pull the engine and tranny out as one unit if I'm not mistaken...nor would I recommend it if you could. Just take the radiator out and separate the engine and tranny and yank the engine out...it's pretty light.

good to know.....

JamesShort · **Posted:** Thu Nov 11, 2010 4:42 pm

Good info in this thread:

http://bbs.legacycentral.org/viewtopic.php?f=5&t=44159

Leads me to believe you do NOT have to pull the ej22 to remove the heads.

EDIT:

Here is a good link about the boxer engine head gasket issues:

http://allwheeldriveauto.com/subaru-hea ... explained/

If you read some of the comments, he says it is very hard to do the job 'right' with the engine in the car.

Apparently EJ22's do not have this problem NEARLY as frequently as the early EJ25's, but it still can happen.

Make sure you put the Subaru coolant conditioner in when you refill the cooling system...it will make your new head gasket last.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

JamesShort wrote:

You can't pull the engine and tranny out as one unit if I'm not mistaken...nor would I recommend it if you could. Just take the radiator out and separate the engine and tranny and yank the engine out...it's pretty light.

+1. with a 4-cyl boxer the trans bolts are crazy easy to get to (compared to an inline 6!)

If you look in the picture I posted you can see the trans still in the car.

MikeWhitney · **Joined:** Wed Aug 20, 2003 9:15 pm **Posts:** 4724

Re: warpage.

Be sure to check both the head and block surfaces with a machinist's straight edge and feeler gauge. I don't know if the subaru manual has the spec for this but I think the Hondas I have checked were a ridiculously small tolerance like 0.008". I measured several heads which were warped from overheating. Probably not an issue on the very short 2-cyl banks, but worth the time to measure.

You're free to borrow my machinist's straight edge.

JamesShort · **Posted:** Thu Nov 11, 2010 11:15 pm

MikeWhitney wrote:

Re: warpage.

Be sure to check both the head and block surfaces with a machinist's straight edge and feeler gauge. I don't know if the subaru manual has the spec for this but I think the Hondas I have checked were a ridiculously small tolerance like 0.008". I measured several heads which were warped from overheating. Probably not an issue on the very short 2-cyl banks, but worth the time to measure.

You're free to borrow my machinist's straight edge.

2006 2.5i FSM I have says warp limit is 0.03mm or 0.001" !

Vincent Keene · **Posted:** Fri Nov 12, 2010 9:42 am

I'd be interested to know how this (warpage measurement) turns out Rodney. I've never heard that a head gasket was a wear item.

JamesShort · **Posted:** Fri Nov 12, 2010 10:04 am

Vincent Keene wrote:

I'd be interested to know how this (warpage measurement) turns out Rodney. I've never heard that a head gasket was a wear item.

So the reason boxer engines are harder on head gaskets is because, unlike v or i engines, where the coolant can flow downward leaving it such that it is not in direct contact with the HG anymore, on boxer engines, the coolant will just 'flatten' in the coolant passage and sit there all night long. Then chemical reactions blah blah blah go on and break down the HG. Subaru has a coolant conditioner that they require for coolant changes to help reduce these chemical reactions.

In that link above, it shows some cool pictures demonstrating this. On the 'bad' HGs, only the lower portion of the holes in the HG for coolant passages show corrosion (ie where the coolant is in contact with when the engine is off and it's just sitting there).

Vincent Keene · **Posted:** Fri Nov 12, 2010 10:06 am

JamesShort wrote:

Vincent Keene wrote:

I'd be interested to know how this (warpage measurement) turns out Rodney. I've never heard that a head gasket was a wear item.

So the reason boxer engines are harder on head gaskets is because, unlike v or i engines, where the coolant can flow downward leaving it such that it is not in direct contact with the HG anymore, on boxer engines, the coolant will just 'flatten' in the coolant passage and sit there all night long. Then chemical reactions blah blah blah go on and break down the HG. Subaru has a coolant conditioner that they require for coolant changes to help reduce these chemical reactions.

In that link above, it shows some cool pictures demonstrating this. On the 'bad' HGs, only the lower portion of the holes in the HG for coolant passages show corrosion (ie where the coolant is in contact with when the engine is off and it's just sitting there).

I guess I'm not familiar enough with the Boxer design.

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