HELP Coolant Pushing Past Head Studs

[mountain4x4]

I finally got the 496 together for my '74 k20 and fired her up today. It started immediately, I followed the cam-break in procedure, then shut her down.

Everything went fine, but coolant was pushing up past ALL the lower 4 head stud nuts (the short ones) on the passenger side. The drivers side head looked fine. I used permatex aviation form-a-gasket to seal the threads, and used ARP's assembly lube on the stud nuts when torqueing the head down. I also used fel-pro head gaskets with hylomar gasket sealer sprayed on the head gaskets to ensure a good seal.

I know I have to remove the head and studs, chase the threads with a tap and start over with new head gaskets, but what could have went wrong here? My machine guy recommended the AV form-a-gasket, is there something better to use? I have used RTV in the past for this and it worked fine, if RTV is better, what type of RTV should be used? Damn, more work!

[mountain4x4]

OK, I think I may have figured out a way to be a lazy bastard and still have this work out without too much trouble.

Since I used Hylomar, the head gasket is pretty much glued down in place. (Hylomar was invented by Mercedes to seal head gaskets, also good for any flange gasket, I use it on the intake manifold gaskets as well...). The head is also held in place by the intake manifold. So, I untorque the head bolts in sequence, than re-torque them to a few foot-lbs, one at a time. Next, take out the studs, again in sequence, clean the threads with a tap, clean the studs with solvent and a brush, apply new sealer to the studs, thread in the studs, and retorque the nut to a few foot pounds. After that process is completed with all the studs, start on the process of re-torquing the head gasket. Done.

I think it will work because the head gasket seal will be maintained by the Hylomar, the head will not be able to move at all, and all the torque will never be taken off the head all at once, except for just the one stud at a time that will be removed to reseal it.The head gaskets I used are pretty pricey, so I'll be saving about $90 right there if it works.

Damn, I cant wait to drive this thing. With the little 174 cu in Supercharger, I'll be making 600 lbs of torque by 2500 rpms. It will limit overall HP to about 550 - 600, but I can live with that.

[KWTMECH]

I always use the GM teflon sealer for the head bolts.

[mountain4x4]

Do you have a pn for the GM sealer?

Thanks in Advance...

[BumpyDodge]

A side note on GM sealers....

I had a tube of GM dealer supplied black rtv silicone I was using to seal the an oil pan. A friend of mine that worked at a Chevy dealership gave me the tube and raved about how it was awesome (It's "pastier" than regular RTV and factory req. for warranty work). I ran out when I needed just a dab more for the timing chain cover corners and used some regular 'ol Permatex RTV. The GM stuff is awesome RTV by itself and it does work great, but...... **WARNING** do not let it come in contact Permatex Hi-temp orange RTV. They don't react well together and will heat up and make nasty smelling smoke! I had to scrape off a bunch of tarry black goo and start over. Thought I'd mention it because you like to use Hylomar, you might want to test it against any other type sealer it might come in contact with.

The Hylomar I have is labled "Hylomar HPF" by permatex -it's blue tinted, w/ molasses consistency. I tried it out to seal an aluminum water pump and it seals/sets nicely, but it doesn't "tack" very well. I can't picture using it on a head gasket without making a mess, is this the same Hylomar you're talking about?

I've used RTV or Form-Gasket No.2 on head bolts (I just looked - it's only rated to 400F, not 600F like Aviation Form-a-gasket). Never tried the dealer supplied teflon the manual calls for. Is it like teflon pipe thread compound or is it really special? No leaks so far, but I imagine factory torque specs would be more accurate with factory sealer.

[mountain4x4]

Thanks for the heads up on that GM sealer. Sounds like an interesting reaction

The Hylomar I used is in a spray can, its colorless. I've never seen the "HPF" stuff before. In looking, I also saw ARP make a thread sealer for this application, I may try to find that stuff. As far as torque specs, I'm using ARP head studs, so sealer wont affect my torque. Theyre spendy, but my previous motor was a 396 with the same supercharger, and it stretched out the stock head bolts, let coolant into my oil and wiped my bearings, bearing particles got in my cylinder bores and scored the walls. The 396 was already .060 over, hence the 454 block I used. It was a really expensive mistake that a set of $100 studs would have eliminated. Overkill, maybe, but good insurance. I also use ARP main studs and 7/16" capscrew rod bolts.

[MrWillys]

Permatex thread sealant Part # 56521.
BUMMER Dude, but I think we've all been there before.

[mountain4x4]

Well, I'm 4 studs into resealing the the threads. Its going pretty smoothly. The tap did bring out some crap that was still in the threads... Since its Sunday, I cant get any ARP, GM or Permatex 565621, so I'm using more AV form-a-gasket. I skimped on it before because I installed the head studs without the heads in place, and using too much made it ooze out the top, then I had to clean it up. I'm using a bit more sealer this time. Also, on the side thats leaking, I didnt tap every hole because the tap cuts a tiny bit more metal out of the threads, which isnt ideal. Apparently not having the threads spottlessly clean isnt ideal either. The other side of the block I did tap every thread for some reason, and its fine. Lesson learned.

So, Should I let the sealant set overnight before I start it up again?

[mountain4x4]

I just fired it up again today. No luck. In fact, some of the studs on the other head started leaking coolant as well. So now I'll have to remove the brake booster to get at that side...

I'm going to order some ARP thread sealer and see if that works. I'm using ARP studs, so hopefully it will do the trick. If that doesnt work, I dont know what the fuck is going on. JB weld the bitches in place? This sucks, another days work. I dont have time for this shit...

[MrWillys]

Originally Posted by mountain4x4

I just fired it up again today. No luck. In fact, some of the studs on the other head started leaking coolant as well. So now I'll have to remove the brake booster to get at that side...

I'm going to order some ARP thread sealer and see if that works. I'm using ARP studs, so hopefully it will do the trick. If that doesnt work, I dont know what the fuck is going on. JB weld the bitches in place? This sucks, another days work. I dont have time for this shit...

Maybe take a break and think about this one. Could you be leaking this from the head gaskets? Could you be creating heat by detonating. I'm just wondering if it could be something other than what your thinking. If it is what you think. Are the studs your using small for some reason? Maybe compare it to the headbolts?
I'd relax and take all approaches here.

[mountain4x4]

I did think of something else. I've had that bottle of form a gasket for 6 months. I have a garage thats only heated when I'm working in it, so it definately was subjected to temps down to 10 degrees or so, maybe it was destroyed by freezing? I'm feeling like a dumb ass for not thinking about this possibility. Most of the studs I removed had NO SIGN of a sealer ever having been there in the first place, others only had a slight trace.

I started it up with initial timing set to 10 degrees, verified by a timing light. I have an A/F ratio gauge, which was centering right aroud stoich, rich when bringing the revs up, lean letting off the throttle. I heard no signs of knock. I torqued the head studs down in 5-6 steps. The engine has never had a load put on it, and has seen 2800 rpms maximum, where timing was topping out at 30 degrees (I have the lightest advance springs in the distributor).

I will mike the headstuds and make sure the diameter is ok, but theyre made by ARP, if you cant trust them to make a good fastener... I also drained the oil and there was no sign of coolant in the oil, even though I'm sure a tiny bit had to get in there from the headstuds that are under the valve covers, so I really dont think the headgaskets could have failed.

I'm thinking to spend a day resealing all 32 studs, if that doesnt work, I'll be removing the heads and replacing the headgaskets, rechecking the head/block surface, etc... This just make me

[MrWillys]

Allright, I'm just thinking about how many times I chased after something to findout it was something different. At least try the thread sealant I quoted you. It's non hardening, but gets kinda crusty when heated.
GOOD LUCK!

[Old Scout]

Originally Posted by mountain4x4

OK, I think I may have figured out a way to be a lazy bastard and still have this work out without too much trouble.

Since I used Hylomar, the head gasket is pretty much glued down in place. (Hylomar was invented by Mercedes to seal head gaskets, also good for any flange gasket, I use it on the intake manifold gaskets as well...).

Hylomar was invented by Rolls Royce for use on there Merlin aircraft engine. The engine suffered from oil leaks when at high altitude from the many different temperature ranges and load ranges of flight.

It's still made in england:
http://www.hylomar.co.uk/contactus.htm

[mountain4x4]

Hylomar was invented by Rolls Royce for use on there Merlin aircraft engine.

Thanks for the link, I stand corrected. My can of Hylomar was a permatex product. It seemed my Hylomar was colorless, but the site says its blue. Of course, my headgaskets are blue as well...

Allright, I'm just thinking about how many times I chased after something to findout it was something different. At least try the thread sealant I quoted you. It's non hardening, but gets kinda crusty when heated.

I think youre right to get people thinking about other things. Whenever I thought I really knew somthing about cars, I was often surprised to find how wrong I was! Thats why I hate stating absolutes when it comes to cars, you can easily be absolutely wrong.

I'm going to try the ARP stuff if I can get it quickly (just cause I have ARP studs), the permatex if not. They both come in 1.69 oz. tubes that look identical, both are teflon based. I wouldnt be surprised if they are the same product. I also am trying to get an ARP thread chaser to clean the threads. If ARP studs, chaser and sealant dont work, and the headgaskets are fine, I'm gonna start crying.

[Magnum_Willys]

Had the exact problem with a rebuilt 496 with head studs and AV cement - and it was professionally assembled by a guy who had done many before. Something with the milled heads, studs, and AV that just didn't work. I yanked the studs and liberally coated everything with Permatex #2 and that did the job.

[spicergear]

You may be surprised what some good Bars Leak will cure...or RTV it really well. Head studs look cooler than hell, but are a real bitch with shit like this AND when they force you to have to notch the header flange!

[mountain4x4]

You may be surprised what some good Bars Leak will cure...or RTV it really well. Head studs look cooler than hell, but are a real bitch with shit like this AND when they force you to have to notch the header flange!

No Doubt... I had to notch the header flanges on a set of ceramic coated Hooker Comp Headers. Not only that, but the passenger side headers don't come out without a major hassle, so I had to mask the exhaust ports and grind it in the vehicle!

The incident with the 396 head bolts stretching lead to this, but I think ARP head bolts would have been just fine. I dont know why its gotta be like this, except I own the truck, and my shit always seems to go like this.

I got the ARP Sealer, ARP Thread Chaser, And a bottle brush I'm gonna soak in Brake Cleaner and clean the threads with before I apply the sealer. If that doesnt work Bars Leak is a very good idea, however much I hate to use it. Or maybe just pack the head bosses with RTV...

I'm gonna do it tomorrow, let it sit overnight and try again, I'll let you know how it goes. Does anyone know if the sealer has to sit overnight? Some of that stuff doesnt set or anything, I think I can fire it up right away, but I dont want to take a chance without knowing.

Thanks for the support, everyone.

[MrWillys]

If you use thread sealant, start it right away. If you use RTV, let the bitch sit for a night at least...
Scott

[spicergear]

I even had a problem with a set of Moroso head bolts they had a wide flange to the head then necked down to like 9/16". I had to grind header flange for those bastards too! GRRRRrrrr

[Buckshot33]

what heads and block are you using mountain? late model blocks water different than early model heads but will still bolt on and vice versa. gotta be carful...

this was just a thought, could just be leaky studs. also, you could always replace the lower studs with bolts...

[mountain4x4]

Buckshot: The block came from a '76 Chevy Motorhome, the heads are from a '71 (or so) 402. Now that I've notched out the header flange for the studs, I guess I'll stick with the studs. I may not have been too clear, the 2nd time I ran the motor, MOST of the studs started leaking on BOTH heads. I think EVERY one would leak eventually the way it is now.

I called ARP, which I didnt think of until today, and they have run into this many times before, but he said most blocks are not a problem. He thinks some blocks were tapped a little on the large side for some reason. (My Block was a virgin) Thanks Chevy

The ARP tech said the best thing to do is clean the studs / block threads as much as possible. I have an ARP thread chaser and a bottle brush I'm gonna soak in Brake Clean and use after the chaser. Then apply a liberal coat of RED RTV. I told him I bought ARP thread sealer, and he recommended AGAINST using it. Torque the heads before it sets. Replace the coolant with plain water. Then warm up the motor up WITHOUT the rad cap on so it doesnt build pressure to help the RTV get a good set. He said to start the motor up immediatly, dont wait overnight! (this sound wrong, but...) He said this will most likely work. If it does not, I guess I'll have to try Bars Leak. Sounds like this should work, though. If it does work, I may follow this procedure on every motor from now on, this is too much trouble to deal with on a regular basis. I'll get it done tomorrow or Friday, and post up the results.

[Triaged]

I always use red loctite on studs.

[Chevyboy51]

how much are they seeping my alum head 406 with studs seeped just a little bit past when I first put it together my motor guy said to run it and get it hot a few times and it would seal and it did

[mountain4x4]

how much are they seeping my alum head 406 with studs seeped just a little bit past when I first put it together my motor guy said to run it and get it hot a few times and it would seal and it did

Hmmm... Gotta give Barz Leak a chance to seal Eh, just messin' with ya. Mine were doing more than "seeping" I'd call it a full on leak.

[mountain4x4]

Yes, the red RTV and the above mentioned process WORKED!

The process took about 12 min per stud x 32 studs = 6.4 hours of work, plus breaks, plus draining all the coolant thru two freeze plugs, plus removing the brake booster, plus removing the headers and plugs, plus removing the exhaust rockers, plus aggravated cursing at my truck made it a long freakin' day, I warned my truck there could be horrible consequenses for it if it didnt run well after this. I'm moving and going back to Engineering School at CU Boulder, so I REALLY have no more time to mess with this thing. I probably woulda parted it out if I had to do anything major after this. Building a performance stroker motor with full floating pistons and file-to fit rings isnt a quick process to begin with, and I did it in 12 days not counting this little problem.

The Blown 496 runs like nothing else I've ever drove or even rode in. This motor IS the definition of throttle response, and using the accelerator peddle is an excercise in throttle modulation.

So far the Holley 850 ported double pumper (closer to 950 after airflow mods) is running just a little rich, but I think I'll keep it that way. Its a blower carb made custom for this motor by AED Performance Carburetors. I highly recommend them, service, product and price are AWESOME. This thing kills my Edelbrock Q-jet.

I'm also using a MSD distributor w/ the 6BTM Box. I have 16 deg. initial timing advance, 20 deg. mechanical advance coming in at 3K RPM, and 1.75 deg retard per pound of boost. Its about 8.5:1 CR with 8-9 lbs boost at WOT. I'm also tuning for 5500' elevation.

Next: Dual 3" Exhaust in stead of Single 3"...

Honestly, its not a DD, and if it goes 50K mi., I'll be happy.

Thank you everyone for your input, I appreciate it