Has anyone ever tried reusing an MLM head gasket?

[jonathan909]

I'm really not looking for a vigorous debate on the relative merits, and I'm quite confident that nobody would ever recommend doing so.

I'd just like to hear from someone who's actually tried it.  If nobody puts their hand up I may look for an opportunity to experiment with the Mahle pair that just came out of this rebuild (with less than a year of service on them).

[Numbchux]

 

 

Yea, been tried a couple times.

I typed "reuse ML..." into Google, it autofilled to "reuse MLS head gasket" and gave thousands of results. I randomly clicked on a page, and found a post on this very forum.

[jonathan909]

Well, lazy me.  Thanks - I'll dig a little further.

[idosubaru]

Sounds like a good follow up repair to an initial repair that suffered in assessment or quality. Lol  

In seriousness. If I had to, I’d prefer to know the history of the engine it’s coming out of. In particular how badly it overheated the first time, and second, if applicable. As much in regards to the engine as well as reusing the gasket. 

[nvu]

Back in honda b16 days, blowing headgaskets was common and they were easy to replace.  If it didn't look deformed or discolored we'd just resurface the head and throw it back on.  I miss those days when gasket replacement costs $100, surfaced heads and all.

[jonathan909]

I took a look, particularly at jelly man's 2013 thread.  Predictably, he got a lot of responses saying "don't do that and here's why".

What he didn't get was what he specifically requested (as have I), which is:  "I did it and here's what happened."

Of course I know what's right, what we're supposed to do, and why.  What I want to know is:  What exactly happens if you ignore the advice and try anyway?  Did it seal at power-up?  If yes, how many miles did you put on it before it failed (if it failed)?  That's all I want.  Not good advice - thousands of those posts around already.  Just actual experience.

Edited April 10, 2021 by jonathan909

[idosubaru]

1 hour ago, jonathan909 said:

I took a look, particularly at jelly man's 2013 thread.  Predictably, he got a lot of responses saying "don't do that and here's why".

What he didn't get was what he specifically requested (as have I), which is:  "I did it and here's what happened."

Of course I know what's right, what we're supposed to do, and why.  What I want to know is:  What exactly happens if you ignore the advice and try?  Did it seal at power-up?  If yes, how many miles did you put on it before it failed (if it failed)?  That's all I want.  Not good advice - thousands of those posts around already.  Just actual experience.

I don’t recall anyone here ever doing it. Maybe you’ll get lucky and get one hit, but numchux suggestion to google is a good one given the guaranteed small sample size of anecdotal replies you’ll get here, if at all. 

[jonathan909]

My point is that googling returns essentially the same answer: Hundreds of people commenting who have never actually tried it either - specifically on a Subaru.

[idosubaru]

2 hours ago, jonathan909 said:

My point is that googling returns essentially the same answer: Hundreds of people commenting who have never actually tried it either - specifically on a Subaru.

Agreed.  Totally get it. I wasn’t saying that like a typical dismissive “go search” blow hard. I’ve been around Subarus and this forum a lot and this is a small data set unlikely to show itself here. 

[1 Lucky Texan]

never read of it being tried.

[nipper]

Never ever EVER reuse a head gasket. By design to seal the crush, so not meant to be reused.

[jonathan909]

Again, not the question.

[GeneralDisorder]

Who's time is worth this experiment? You are going to risk ~16 hours of labor for $100. 

What's your time worth exactly? 

GD

 

[jonathan909]

The answer to that question is actually very complicated.  If I'm billing it out, a lot.  At the other end of the scale, there are thing I'll do for friends for free that I would refuse to accept as paying work because it's too tedious and unpleasant and/or I know the client would be a PITA.  And I've done a lot of volunteer work, notably for a Bay Area performance art group, for which I not only wasn't paid, but I had to cover my own expenses, including travel.  In other words, if I find something incredible enough to work on, I'll pay to do it.

I do R+D and startups, so I'm wired to accept varying likelihoods of success - or failure.  I don't as a rule undertake something that has a high probability of failure, but again, there can be mitigating factors that make it acceptably attractive, like the people I get to work with and what we might learn along the way.  This is sort of in that group.  I know the odds of "success" are poor, but as we seem to have learned so far in this conversation, there may well be zero extant data points, and the idea of gathering the first is kind of attractive to me.

I get that many here, and you in particular, may find this a bu!!sh!t argument - I understand completely.  And (esp. now that it's almost summer) I've got a lot of important stuff on my plate, so I'm not in a big rush to do this.  Just keeping it in mind should the the opportunity, inclination, and a little extra time coincide.

Edited April 15, 2021 by jonathan909

[idosubaru]

1 hour ago, jonathan909 said:

 as we seem to have learned so far in this conversation, there may well be zero extant data points, and the idea of gathering the first is kind of attractive to me.

here's a few I found with a cursory glance,  presumably there are more with a little effort:

https://www.subaruoutback.org/threads/your-opinions-on-re-using-head-gasket.174570/

 

https://somespeed.com/questions/if-i-installed-a-headgasket-upside-down-and-torque-it-and-noticed-later-on-i-installed-it-wrong-can-i-still-use-the-same-headgasket/

[jonathan909]

4 minutes ago, idosubaru said:

here's a few I found with a cursory glance,  presumably there are more with a little effort:

Now we're starting to go in circles.  This is the thread I referenced earlier - he didn't find anyone who'd actually tried either

https://www.subaruoutback.org/threads/your-opinions-on-re-using-head-gasket.174570/

This is funny - that's my thread (I'm outinthewoods), started with my first '99 OBW ten years ago.  The problem was solved with a used short block - and new gaskets.  Interesting to note that there was one respondent who'd tried successfully (I'd forgotten about that).  So that's one data point.

https://somespeed.com/questions/if-i-installed-a-headgasket-upside-down-and-torque-it-and-noticed-later-on-i-installed-it-wrong-can-i-still-use-the-same-headgasket/

That one deviated a lot into discussion of bolt re-use.  But there was one guy in there who'd recycled a head gasket and won.  Two data points.

[jonathan909]

Btw, all those exchanges about upside-down gaskets were a bit close to home.  With my first EJ25D rebuild a couple of years ago I actually managed to put a head on upside-down.  Had a towel on top of it so crap wouldn't fall into the ports, cleverly hiding the exhaust ports from myself - also, the timing sprockets weren't on yet.  The giveaway should have been that a couple of the bolts were rubbing the holes in the gasket rather than being centered - the gaskets aren't perfectly symmetrical.  Fortunately, I caught it before torquing.

Not the dumbest thing I've done with a car, but up there.

[GeneralDisorder]

There's no knowledge to gain here. 

You might get away with it and you might not. 

Depends on the surface condition of the block and heads, and how accurately the gasket is located with respect to where it was the last time. The gasket is there (obviously) to take up imperfections in the surface of the block and the surface of the head. That's it's job. If the surfaces were *perfect* then no gasket would be required. In fact many nitro-methane top-fuel engines don't use gaskets - they use highly accurate and highly engineered mirror finish surfaces instead. So if the gasket surface is uniform, the gasket is located exactly where it was the previous install, and the gasket did not experience plastic deformation - you will be successful. If one or more of those qualifications is not true you won't. There is NO mystery here. 

It's a bad gamble, and one that you might win or lose. But a gamble not worth the $100 savings for the loss of two days worth of work if you lose. There's no significant data to be gathered from one trial of this hypothesis. You would have to repeat the experiment many times over to have any useful statistics - which you clearly are not in a position to perform. One anecdotal success or failure does not a scientific theory make. It would therefore be a waste of time. 

GD

[idosubaru]

9 hours ago, GeneralDisorder said:

If the surfaces were *perfect* then no gasket would be required.

Like those 80's/90's Volvo brake calipers - two machined parts bolted together with brake fluid passages running through them...and no gasket or orings at all?  I opened one up one time and it would never seal when I tried to put it back together.  That was pretty wild, I wasn't expecting it. 

[Lightning Racer]

No head gaskets in this one:

 

Edited April 16, 2021 by Lightning Racer