Is the OEM Toyota head gasket an MLS gasket?
Why do a head gasket as preventative maintenance? (1 Viewer)
- Thread starter nodor
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No, but the Cometic one is.
Is the Cometic the generally recommended head gasket over OEM cause it’s MLS? The head is getting resurfaced and a valve job.
Opinions differ. If you're going to boost, seems like consensus is to do the Cometic. If you do an MLS gasket, you have to get the block decked to make sure it is absolutely flat (and get rid of old gasket pitting). Also have to make sure the head is absolutely flat.
If you're not going to go that route, you should do the OE gasket. I am using the OE gasket. I cleaned the block surface and had the head checked for flatness at a machine shop.
Don't get too excited with this approach. Both 80's i own show up as 2WD on the Toyota website and neither shows any maintenance even though i have all the dealer receipts...
Yep - and the irresponsible dirt bags (actually nice people I'm sure, but they get cursed frequently) who tried to run the truck into the ground before you owned it certainly weren't taking it to the dealership for service, if they did any at all.
yeah. Block is not pulled. No plans for boost unless I do a rebuild and somehow come into about 10k. I’m sticking with OEM.
Anyone know if the Lexus owner online group is more helpful than this one? I've heard it may show maintenance that doesn't show up on Carfax.
Best of luck. Lots of good threads and OTRAMM's videos on how to do it.
yep. I already pulled the head. (Thanks OTRAMM) wasn’t too hard. This all started cause: “I was gonna pull the intake manifold to replace the PHH”.
^^^^
Yes, if going MLS both surfaces MUST be flat. And generally the Ra factor will need to be different too (smoother for a MLS gasket).
Yes, the machine shop asked me which type of head gasket I was planning on using. I've done head gaskets on 3.slows and Subbie engines and have never heard about getting the block decked for MLS gaskets.
Maybe those folks are a slightly different breed.
Maybe those folks are a slightly different breed.
According to Cometic "A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design." I don't know exactly how smooth that is, but looking at most 1fz blocks, they do look pretty pitted when the stock gasket comes off.
:edit: 50RA looks pretty darn smooth:
:edit: 50RA looks pretty darn smooth:
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The issue I'm having is that I would absolutely love to do it myself... if I had the time. I'm not someone that would be able to just do the head gasket without wanting to do EVERYTHING I can while in there. I just don't have time to do that. If I did I probably would have started the project awhile ago. So I'm stuck in this position where I put off the head gasket as preventative maintenance until I have the time to do it myself (which may be a very long time from now), go ahead and pay someone else to do it now, or just wait until it fails and I'm forced to do so. I'm also very paranoid and have a hard time convincing myself to give my truck to someone else to do it when I know I could do it myself and know exactly what and how everything was done... which leads to me just putting it off longer.
Paranoid and Procrastination.....what a combo.
I made a list of 'to do while in there' items, ordered and received all parts before removing the head on mine.
IF you have a shop that can do the head work quickly then all the rest of it (to do items) could all be done a few long days.
If you can't arrange for that amount of time (maybe take some vacation time) then you really have no choice but to have someone else do it.
And yes, they will NOT do it as carefully as you would.
Mine with 290k (94) and 147k (97) both suck oil through the valve guide seals. I don't know how any FZEs with original parts can't be using some oil and wouldn't benefit from the valve guide seal replacement. That alone could be justification for pulling the head. There is an old thread showing the difference in the holes in the HG next to #1 and#6 cylinders on the improved design HG. AFAIK when I look at aftermarket HG they use the old design. Also in an old thread is that the HG failure can be caused by the fact that an aluminum head this long (three feet?!) expands/contracts and moves against the iron block a considerable distance every heat cycle causing the gasket to just "wear"
Mine just crossed 316k miles this past Friday (1996 model) and that's when it failed. I too was lucky in that I had just hit traffic and come to a stop when it happened, right at an exit with a gas station. Pulled off quickly and shut it down. It wasn't a crazy amount coming out but it was at #6 so I figured it had finally happened. It was already on my list as I'll be taking a pretty long road trip next month and assumed I was already on borrowed time. Head is at the machine shop now while OEM gasket set and lots of other odds and ends are enroute. Based on my coolant when I changed the radiator a few weeks ago, it was already on the way out. Just do it for peace of mind if you're able to park it for a week or two while you tear it down and wait on machine work.
pretty much what I was going to write. The #6 cylinder, yes, that's the area where most of our trucks tend to lose HG sealing. This happens when the truck overheats. Invest in a new radiator, hoses, quality coolant, thermostat and FAN CLUTCH. An over heated engine will cook a head gasket if it has 100 or 1 million miles.
Considering that the FSM calls for a complete tear down and rebuild of the engine at 186Kmi, and your HG blew out at 316K that's a touch over a 1.5x service life.
Not too shabby.
Not too shabby.
This. Mine was using a quart every 1500 miles. Now I was going to do the head gasket, radiator, wiring harness, and fuel injectors with all new hoses, belts. When it came down to it, I ended up doing the whole thing. Even manifold back exhaust. That was 6 years ago and it’s got about 42k on it and I don’t use a drop of oil between changes. Absolutely nothing. It goes 6k on T6 and the dipstick stays at that top line to the point that I’m actually shocked. Yes, it cost a lot but you seen what a new 4Runner cost? I stopped at Boulder Toyota for an oil filter and they had a Trail Edition in there that was $62,000. My rationale was that I did indeed use it and the thing was 20 years old and while they are reliable, there are just an enormous amount of parts that suffer with heat cycles and use over that huge amount of time.
