7MGE Head Gasket Replacement
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That’s what I’m not sure about… a buddy of mine said to use a head gasket sealer to seal the new gasket in… the only sealer for head gaskets I’m aware of is a head gasket repair, however, I have a new head gasket. So for installation what should I do? Just drop the new gasket on and that’s it?
That Titan head gasket is a rebranded Cometic.
It is already coated on both sides with Viton, not necessary to coat it in any type of spray or sealant.
Those that re-use metal head gaskets sometimes spray coating back on the sides of the old one. As the Viton coating would no longer be viable.
You should find out from your machinist how much material was removed after resurfacing the block and head.
You may be better off getting the 1.4mm thickness vs the 2.0mm.
Also depends on if any machining was done prior to your rebuild.
Also has the potential to affect crank to cam degree offset as the spacing in tooth on the timing belt is fixed and unchangeable.
Yours especially being a naturally aspirated 7MGE, increasing the thickness unnecessarily will lower your compression ratio. Potentially dropping your engine power.
Though if you are later switching to NA-T, then would be offset by forced induction.
Make sure that the head and block are machined to the appropriate RA surface required by Cometic. (Call them and find out what the min spec is)
All things to keep in mind and plan for.
It is already coated on both sides with Viton, not necessary to coat it in any type of spray or sealant.
Those that re-use metal head gaskets sometimes spray coating back on the sides of the old one. As the Viton coating would no longer be viable.
You should find out from your machinist how much material was removed after resurfacing the block and head.
You may be better off getting the 1.4mm thickness vs the 2.0mm.
Also depends on if any machining was done prior to your rebuild.
Also has the potential to affect crank to cam degree offset as the spacing in tooth on the timing belt is fixed and unchangeable.
Yours especially being a naturally aspirated 7MGE, increasing the thickness unnecessarily will lower your compression ratio. Potentially dropping your engine power.
Though if you are later switching to NA-T, then would be offset by forced induction.
Make sure that the head and block are machined to the appropriate RA surface required by Cometic. (Call them and find out what the min spec is)
All things to keep in mind and plan for.
Thank you!! That was very helpful!! I plan to go NA-T but can’t quite figure out how I would do so… what parts to purchase and how to fix these new compression issues. For now, however, would giving the car for air and fuel fix the compression issues? Or would you recommend I run a 1.4mm head gasket instead. Only problem is that I’d be worried about the head gasket failing again.
You need to find out if any material has ever been removed from the head or block prior.
Then you need to get from the machine shop how much material was resurfaced off the head and block.
This will give you the answer as to what thickness head gasket to purchase.
The engine builder should already know all of this.
Then you need to get from the machine shop how much material was resurfaced off the head and block.
This will give you the answer as to what thickness head gasket to purchase.
The engine builder should already know all of this.
I doubt there was any material removed at all… the pro opus owner was the only owner before me and hardly got the car serviced let alone rebuilt… it’s safe to assume it’s as stock as it gets… with this, should I run the gasket I bought? If so, I’d have to get the block machined and material removed… would this be something you would recommend? The block isn’t even out of the car… and I need it to be ready by next month… on this crunch for time I’d love to keep the block in… what should I do, what would you do?
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You have to get the block and head machined for a metal headgasket, period.. full-stop. With your timeline, id doubt youd even have enough time to buy an oem headgasket, get the head machined, scrape the old gasket bits off the block, chase the block threads and put it all back together.
Or... you can just slap the gasket on and send it until it blows and do it all over again properly. Let us know how long that takes though and what symptoms start first lol!
Or... you can just slap the gasket on and send it until it blows and do it all over again properly. Let us know how long that takes though and what symptoms start first lol!
Eh? So it was a perfectly running engine and all you're doing is replacing the head gasket preventatively? If yes, then clean the head's mating surface to bare metal, ditto the block surface. Borrow a straight edge and some feeler guages ($12) and check for flatness. If flat, buy a NORMAL head gasket - not a metal one - and simply reassemble.
You say you have big plans. Turbo. Nitrous. Uber cool racing suspension. How about you just get the car running and then one day IF you decide to do all that, then it will need some work, including stripping the engine down. So no point in mucking about with a metal head gasket at this point. At all. You can do what I describe in a couple weeks if you stop for coffee and sleep. Otherwise this is going to be a garage queen in parts for years.
Put a normal head gasket on it and drive it.
You say you have big plans. Turbo. Nitrous. Uber cool racing suspension. How about you just get the car running and then one day IF you decide to do all that, then it will need some work, including stripping the engine down. So no point in mucking about with a metal head gasket at this point. At all. You can do what I describe in a couple weeks if you stop for coffee and sleep. Otherwise this is going to be a garage queen in parts for years.
Put a normal head gasket on it and drive it.
I've seen people get a flat granite stone from stoneworking shops or whatever you call them, you can fork out more money for one that comes with a certificate of flatness, then they just gently lap the surface for hours until they get the finish needed. There are quite a few youtube videos on how to lap the surface with such stones in such a way that you don't go over the same area too many times, causing unevenness. I can't seem to find anyone who's surfaced a block in the car for a metal gasket, but I wouldn't be surprised if someone out there has done it, but just hasn't posted about it on the internet.
But if you're keeping it NA, +1 what Doug said. May be worth just ordering a regular gasket and calling it a day. Hell, the stock gasket is apparently capable of a decent amount of boost once the head bolts are retorqued (a guy on this forum years ago who's got studs + oem gasket on 12 psi boost for 50,000 km no issues).
For what it's worth, I did this few months ago; top end rebuild without pulling the block. Just got a razor scraper from work, and kept scraping over the surface until it was clean. I didn't even use any sandpaper or a sanding block, just a razor and a bit of brake cleaner. At least for a composite/graphite gasket, it doesn't have to look shiny, the gasket doesn't care what the surface looks like...only that it's clean, flat and straight. Metal gasket is a different story though. But anyway, I just spent at least 4 hours over a few days scraping away. Since it's an iron block, it is quite resistant to gouging from the razor. The aluminium pistons not so much lol. I figured it was good enough when the razor would no longer pick up any crap off the deck. Main areas to pay attention to are where the metal sealing rings of the gasket will sit. Those spots are the most important to be spotless. There was actually a slight amount of buildup where the metal sealing rings sat on my block, both around the cylinder bores and coolant passages, I think I could just feel it with my fingernail but otherwise I just shrugged since there really wasn't much else I could do at that point.
Good idea to use shaving cream or assembly lube to plug the front oil hole that feeds oil into the head and stop crap getting in, but not essential. Could also use something to seal up the piston bores. A bit of crud went down the front oil hole in my engine, and a lot went down the coolant passages and the front slit leading to the sump but I'm guessing the oil filter caught everything once the engine was running. The crud is old graphite gasket material anyway, stuff that wouldn't really kill bearings as far as I'm aware. It's metal shavings that you need to worry about and I can't think of how you'd get that short of running a cheese grater to the fire rings on the old gasket and sprinkling over the block.
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The above pic is how I left the block while I scraped away. You can see the marks left from the gasket sealing rings, I could barely feel them with my nail. I just scraped and scraped until the rusty brown stuff from the coolant was gone, and the checkerboard pattern from the gasket was gone. It seems to have worked so far, because that was a few months ago at96-97,000 94,500 km. My car is now at little over 100,000 km and I can safely say at least two thirds of that was flooring it up and down mountain roads. The most amount of damage this rebuild has resulted in was when the old hood struts collapsed when I cranked the engine after putting everything back and it bucked enough to make the hood fall down and smash my timing light to bits.
But if you're keeping it NA, +1 what Doug said. May be worth just ordering a regular gasket and calling it a day. Hell, the stock gasket is apparently capable of a decent amount of boost once the head bolts are retorqued (a guy on this forum years ago who's got studs + oem gasket on 12 psi boost for 50,000 km no issues).
For what it's worth, I did this few months ago; top end rebuild without pulling the block. Just got a razor scraper from work, and kept scraping over the surface until it was clean. I didn't even use any sandpaper or a sanding block, just a razor and a bit of brake cleaner. At least for a composite/graphite gasket, it doesn't have to look shiny, the gasket doesn't care what the surface looks like...only that it's clean, flat and straight. Metal gasket is a different story though. But anyway, I just spent at least 4 hours over a few days scraping away. Since it's an iron block, it is quite resistant to gouging from the razor. The aluminium pistons not so much lol. I figured it was good enough when the razor would no longer pick up any crap off the deck. Main areas to pay attention to are where the metal sealing rings of the gasket will sit. Those spots are the most important to be spotless. There was actually a slight amount of buildup where the metal sealing rings sat on my block, both around the cylinder bores and coolant passages, I think I could just feel it with my fingernail but otherwise I just shrugged since there really wasn't much else I could do at that point.
Good idea to use shaving cream or assembly lube to plug the front oil hole that feeds oil into the head and stop crap getting in, but not essential. Could also use something to seal up the piston bores. A bit of crud went down the front oil hole in my engine, and a lot went down the coolant passages and the front slit leading to the sump but I'm guessing the oil filter caught everything once the engine was running. The crud is old graphite gasket material anyway, stuff that wouldn't really kill bearings as far as I'm aware. It's metal shavings that you need to worry about and I can't think of how you'd get that short of running a cheese grater to the fire rings on the old gasket and sprinkling over the block.
The above pic is how I left the block while I scraped away. You can see the marks left from the gasket sealing rings, I could barely feel them with my nail. I just scraped and scraped until the rusty brown stuff from the coolant was gone, and the checkerboard pattern from the gasket was gone. It seems to have worked so far, because that was a few months ago at
Almost forgot, when I cleaned out the stud holes in the block I used a cheap thread tap from driftmotion - it may be preferable to get the ARP thread chaser even though it is about 10 times more expensive, because taps will cut away too much material if you have to keep doing it over and over, I mean you shouldn't have to do this again but who knows. Chasers are specifically designed to clean only. Each hole I did two turns, then one turn back, repeat till I bottomed out. Used compressed air and an air gun to blast out all the debris, making sure to blow away the resulting cloud of dust away from the block. Didn't want metal shavings in the engine.
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