Topic: Any advice for exhaust manifold gasket on 20R

[jmac80]

Anybody got any advice on doing the exhaust manifold gasket on a 20R?

I ordered the gasket and set of studs/nuts from LC.

I was lazy and paid a Big O to do this about two years ago.  Well a small leak started a while back. and then on Sunday while coming back from Tahoe, I threw a fan/alternator belt and truck got hot.  Temp didn't peg out but got into the red before I noticed.  Anyway, the small leak is now a big leak and needs to be addressed.....hopefully head is still true.  The guy that did it two years back replaced a broken stud with a Grade 8/Class 10.9 bolt (so he said); so at the very least this one should get a new stud.

Should I try and replace all the studs with new?  Do you guys red locktite the stud into the head?  Antiseeze on the manifold/nut side?

Any helpful tricks on getting a stud out....will a heat gut get hot enough to help or do you need a torch?.....I know you don't want to get that aluminum too hot.

Also, going to try and rebuild the old carb and retap thermostat housing bolt threads while the breather is off.....I've been too lazy for far too long for a DD.

Thanks in advance and Happy New Year guys!

[300k]

I've never used their exhaust stud set, but the one thing I don't care for with LCE is their hardware. Their header stud kit looks different from the usual hardware store special that they throw in with kit orders, but for 17 dollars I don't know.

I pulled my motor apart and sprayed all the bolts down with a penetrating oil for a few days before (WD40 brand, ran out of PB)...that might have helped but lucky enough for me the manifold wasn't actually torqued down so I don't think I needed it, and no bolts broke.

I'd spray it down and drive the truck around, repeat a few times. my engine melted and wouldn't start again or I would have done that

good luck!

[emsvitil]

The problem is that the studs pull out of the aluminum heads and the manifold warps

After 2 pulled on mine,  I installed threaded inserts for all the studs and had the manifold surfaced.

[Gnarly4X]

Anybody got any advice on doing the exhaust manifold gasket on a 20R?

I ordered the gasket and set of studs/nuts from LC.

I was lazy and paid a Big O to do this about two years ago.  Well a small leak started a while back. and then on Sunday while coming back from Tahoe, I threw a fan/alternator belt and truck got hot.  Temp didn't peg out but got into the red before I noticed.  Anyway, the small leak is now a big leak and needs to be addressed.....hopefully head is still true.  The guy that did it two years back replaced a broken stud with a Grade 8/Class 10.9 bolt (so he said); so at the very least this one should get a new stud.

Should I try and replace all the studs with new?  Do you guys red locktite the stud into the head?  Antiseeze on the manifold/nut side?

Any helpful tricks on getting a stud out....will a heat gut get hot enough to help or do you need a torch?.....I know you don't want to get that aluminum too hot.

Also, going to try and rebuild the old carb and retap thermostat housing bolt threads while the breather is off.....I've been too lazy for far too long for a DD.

Thanks in advance and Happy New Year guys!

This has already been discussed... search for the recent thread!!

Gnarls.

[jmac80 [OP]]

This has already been discussed... search for the recent thread!!

Gnarls.

Gotcha Gnarls.  Your link in the exhaust manifold thread didn't work but I tracked your posts on your 22R buildup thread.  I think I'll see what the LCE hardware looks like and what everything looks like on the truck and go from there (heat shield currently still installed, so can't see anything).  Ideally, I'll just use one of the studs to replace the bolt used previously, and either go down your jam nut route if the LCE nuts look like BS or use their nuts (Gnarls is shaking his head saying, use the damn jam nut setup).

Ok Gnarls, don't kill me....two more questions,

If the manifold is not true, will this be obvious if checked with something like a steel ruler/straightedge? What's the general consensus on helicoil vs threadsert, if I have to go that route.....planning for the worst?

Have a good weekend folks

[Gnarly4X]

Don't remove the studs unless they are loose. HC or TC are both fine.
red locktite on head threads, anti-seize on manifold threads. Flat check manifold. Use Remflex gasket. Don't use factory nuts.

Gnarls.

[jmac80 [OP]]

ughhh, back again.  I'm looking at this diagram and getting confused.  Have any of ya'll done this on a 20R?  Check out this diagram I got from dealer, it looks part 17167 insulator sits between the manifold and the gasket.  How the hell does that seal?  The LCE gasket has a shield built on it that looks to replace the 17168 insulator

http://www.lceperformance.com/Exhaust-Gasket-20R-22R-RE-75-84-p/1044000.htm

So do I leave the 17197 insulator in there or leave it and the 17168 insulator off?  Also, truck is a CA truck so it may have that weird double manifold setup that's shown.....I may be having twice the fun on this guy.

[jimbo74]

I just want to throw this out there, but red loctite isn't going to do squat on an exhaust manifold.... red is typically the high strength stuff, but it is defeated with heat, which the manifold bolt will be saturated with all the time... all it is going to do, is going to effect proper torque of the stud

if your hole is stripped, you are hosed.... time-serts are the best fix, but they are not cheap, and are time consuming.. you may not have proper access without removing the head....

[Gnarly4X]

Red Loctite is good for reducing the corrosion. It will also help prevent the stud from spinning loose in the head. You should be very careful when torquing the studs anyway. Drilling and tapping the head on the engine is very tricky and difficult for me. I've done it more than a dozen times. I've used both helicoil and time serts.

Gnarls.

[emsvitil]

FYI

I did the threaded inserts without removing the head.

Start with drill bit that fits hole, then keep increasing drill bit size until you get to the correct size.

I had to drill the rear holes by gloved hand (not even a 90 drill adapter would fit)


I also switched to 3/8 studs (from 10mm) and threaded inserts because

1.  they were cheaper (I just used 3/8 stainless threaded rod cut to size)
2.  3/8 threaded insert is smaller OD than 10mm and didn't have to drill (by hand) as much.


I used red Loctite on threaded insert to head and blue on stud to insert.

I don't think they get hot enough to break down the Loctite because they'll be cylinder head temp.

[jmac80 [OP]]

Back from the weekend of one failed duck hunt and one failed manifold gasket replacement.  What do you guys think about this.  So the set up matched the non-CA part of the diagram.  The header does sit direction onto that "insulator" piece.  The gasket is then supposed to sit between the insulator and head.  There were two gaskets in mine, one on each side of the insulator.  Insulator was found to be burnt out between between a couple of ports and had one crack (you can see in image).  I decided to move forward with one gasket only as shown in diagram and use that copper RTV on the burnt out port and cracks area.  The LCE gasket looked nice by the way.  I will have to remove the heatshield for use with the insulator parts (need to keep all this BS to pass smog).

Now, only front three and middle manifold nuts were on and were hand tight or less.  Studs missing from all three holes around cylinder 3 and 4 ports.  Surprisingly, all holes still have threads.  One was extremely dirty but after working a stud in and out several times it seemed to be straightened out.  Here is the odd thing, the studs have a short and long side, and my understanding is the short side goes into the head.  Three of the four head holes seemed deep enough to screw the studs in backwards (long threads into head) and I could feel threads deep into the holes when running a piece of plastic in there.  Also, stock studs had much less threads on manifold side compared to the long side of the LCE studs, but suspect this has to do with fitting to LCE headers.  So anyway, upon trying to put in the stud, once the non-threaded portion reached the edge of the head I could not hit the 10 ft-lbs and the stud pulled into the head.  After seeing the non-threaded section entering the head I stopped and wanted to get some feedback on what's going on here.  You can see hole with first couple of threads flattened in 2nd image.
 

[jmac80 [OP]]

burnt insulator

[Gnarly4X]

Hey jmac80,

There is no point to torquing the studs to 10 lbs in an old head, they are not clamping anything.  Use Red Loctite on those threads, tighten the stud just snug with double hex nuts.  Red Loctite sets up in about 10 minutes, and fully cures in 24 hours.  I would let the studs cure completely, leaving the double nuts on the stud until your are ready to remove them and then use hex nuts, one being a locking nut, to install the exhaust manifold. I use a very light coating of anti-seize on the manifold threads.  If you use the Toyota factory nuts, they will very likely spin the studs inside the head when you go to loosen them, and worse, they will spin the studs inside the head when you tighten them.

I install the manifold, or the DT header nuts with lighter than spec torque.  I check and lightly retorque the nuts after an hour of run time while the engine in warm.  I recheck the nuts again after 50 to 100 miles.  I recheck them again until they are snug.  I recheck them about every couple months because the header gasket will typically shrink slightly over multiple heat cycles and mileage.

Everyone has an opinion on this issue, that’s mine based on dealing with the problem on all three of my 22s.

Gnarls.

[jmac80 [OP]]

Well, already did something yesterday evening after not hearing from you guys yesterday morning....no sweat I appreciate all the help and advice I can get.  I figured ya'll were sick of jacking with me.  But after all it sounds like everyone's on about the same page or at least combined on this page...bad joke.  I ended up doing this (it's a combo of all of our thoughts, opinions, and other BSings).

Since the holes were so deep and had threads all the way through, I put the LCE studs in backwards and used the double nut to get just a little over finger tight. The shoulder (non-threaded portion) of theirs is shorter than stock and their "head" side plus shoulder is same as manifold length side on stock.  Theirs also appears to be Grade 5 and the outer gold coating came off w/ WD40.  They went in backwards with only about 2 threads still proud of the head.  I used Ed's suggestion of the blue loctite, thinking "well, if it backs out I can try again with the red before resorting to drilling and inserts".  I'm thinking someone just drilled and tapped the stock holes deeper here in an attempt to avoid inserts/use what they had on hand, just guessing.

I left this to set up over night (it was raining so I had gotten wet enough at this point).  I didn't have enough old nuts on hand, but Gnarls' suggestion about pulling the double nuts off the next day (or even 30 minutes later) would have been better than my removing immediately, oh well, next time. 

I plan to buy that copper RTV at lunch today and put on all three surfaces head/gasket/heat shield/manifold and torque down to something like 20 ft-lbs, drive around West Oakland and see what shenanigans are going on in the neighborhood, and retorque.  I will try and fill burn out areas and cracks on heat shield with the copper RTV.

[Gnarly4X]

...I'm thinking someone just drilled and tapped the stock holes deeper here in an attempt to avoid inserts/use what they had on hand, just guessing.

When and if you drill those studs holes in the head, be VERY careful NOT to drill further than the depth of the stock hole, otherwise you could drill through the head!!

Gnarls.

[jmac80 [OP]]

I get an F in shade tree mechanic.

I put the copper silicone on all the surfaces and  torqued down manifold to 25 ft-lbs.  Went inside to eat dinner and half way through realized....forgot the anti-seeze

Well, I let the silicone cure for about an hour and half and then backed each nut off and applied the antiseeze and retorqued to 25 ft-lbs.  Did one at a time in an attempt to minimize negative effect.  I plan to retighten at 25 ft-lbs again this afternoon (drove to work this morning, no issues other than sticky new gasket).

I got lucky, only one of the new studs backed instead of nut coming off stud.....I just broke the lock nut free, put more loctite on thread, and put back in with fingers as far as I could and then finished with nut at the 25 ft-lbs.....this may not have occurred if I let the loctite set up before removing jam nuts (Gnarls is right again). 

Needless to say, I may get some experience with this dude in the near future given those nuts were pulled off/reused....live and learn right.

I took a couple of pics to show how the backwards stud approach worked for me (but like Gnarls said, you really shouldn't drill that deep into head) and how the shorter shoulder allowed for a few threads to sit proud.

OK so who wants to bet on how long this guy holds up for.....I'll update this if something interesting happens with it.

[jmac80 [OP]]

Oh yeah, Thanks for everyone's input.

[Gnarly4X]

Hey jmac80,

An "F" is for Fubar... that means you caused major damage.  A "D" for Dummy... that means someone else caught your mistake.  You get a C minus... that's because you made a mistake and then "Caught" it while in the act!

There is a reason the exhaust manifold studs have two different length of threads.  The shorter side goes into the head at a specific depth. The boss on the stud then stops it from going too far into the back of head and allows tightening at the face of the head – not inside the threads of the head – possibly cracking that small area inside the head.  With the lack of full threads where the manifold – or header – will sit, you should make sure you have enough threads for the nuts to torque down on the gasket and flange.

I should have mentioned, the FSM spec says 33 lbs of torque on the exhaust manifold to head - that is WAY too much torque in my experience.  25 lbs. may be pushing it in an old head, and that is assuming you are not using factory nuts or clamping nuts, and using a little anti-sieze on the manifold threads.  I would never use anti-seize on the head stud threads.  I do multiple re-torques and checks after installing the manifold or header until the nuts take a set, and it may take several days or several 100 miles before they are finally nice and tight and there are no exhaust leaks.

Any time I am doing threads with Loctite, thread sealant, or anti-seize, I wire brush and clean the threads with carb cleaner, MEK, or lacquer thinner, so they are super clean before applying any thing.  By hand, I also spin a nut on all threads to make sure they are smooth and have no damage – BEFORE attempting to install them.

That’s just my opinion – it may be worthless. 

Gnarls.