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I have a 1970 TR6R that has a top end oil leak. The head is flat, so there is no problem there. I bought a CovSeal gasket kit. On the package, it says to assemble dry. Should I follow that or use a gasket sealer? If so what gasket sealer? The kit has a copper head gasket.

Thanks, Jim from Pasadena

I tried dry for the Covseals, got a "weep". Repeated with new Covseals and Ultragray sealer, dry now
Doug

I have dry Covseals on my 66 Bonnie, dry as a bone.

I have them on my 67 tr6c. They don’t leak at all. Put them on dry and use a torque wrench

Have you re-torqued the head bolts?

Hi Jim -

Welcome!

I put a *light* coating of grease (just enough to dampen the paper) on the CovSeal gaskets. No leaks, and the gasket comes off much easier (no scraping of paper off the alloy) upon disassembly.

Steve

"Top end oil leak".... where exactly is the leak coming from?

Rocker box?

Seals?

Could you tell us more please

It could have been the intake rocker box, but I think it was the push rod tube. In any case the head now off of the motorcycle and I am now in the process of cleaning parts. I guess I should give a little back ground on this bike. I have owned it for about 20 years now. For the first 10 years it was a reliable and oil tight ( for a British engine). Then one day a wrist pin clip came loose and ruined the left cylinder and piston . I pulled the top end apart and had a machine shop resleve the barrels to stock diameter and I put every back together with new pistons. At the time I was unaware of the importance push rod tube seal compression. By sheer dumb luck, everything was close enough. The engine was oil tight for the first few hundred miles and then the rear tube started to leak a little bit. The leak has gotten progressively worse over the years. Based on the articles I have read, the bike has the correct head, tube and block combination for a 70 . Also, I check the head thickness and flatness, which are both ok.

Jim from Pasadena

Sounds like you have done everything (and checked) correctly.

I make sure that all surfaces are flat and clean with aceton or alcohol prior to installing the CovSeal or any gasket set.

It is very possible that your push rod tube seals had started to corrode and break down thus causing a leak more and more over time.

When a leak is evident, I tend to wash the engine and remove all oil, then go for a quick ride to properly isolate the leak.. while riding turbulence can cause oil to work its way into places foreign giving you a false sign of where the "real" leak is.

Push rod tube crush is very important.. not only to seal but to ensure torque is applied to the barrel / head gasket and not on the tubes causing a warped head.

If you feel the need to use sealer, I recommend Hylomar or Gasgacinch (I hope I spelled it correctly)

Hi Doug, I've had mixed results with cov-seal rocker box gaskets. I've installed dry & the alloy of head, boxes was perfectly cleaned. None leaked bad, but several sweated a slight oil which collected some dirt. I started to use Mercedes sealant on them which would correspond to Loctite 510. Have had 100% perfect results. Again surfaces must be perfectly clean. A light smear on gasket. It will slightly soak in. Cov seal gaskets have compound such it sort of vulcanizes to the metal & shouldn't leak, but I find these sealants really help.

The Mercedes or Loctite 510 is quite good on paper cly base gaskets as well. I always use it now. Will prevent seeps & sweating around gasket. I also put on the 4 cyl base stud threads that that are open to crank case. Stops oil migrating up. The nice thing is you get a very long working time to install cylinder without sealant curing too fast or skinning over.

Also these sealants will almost 100% of time seal cyl base nuts that are seeping oil. Remove nut & washer (if used). very gently blow out oil residue around stud if possible or soak it out with a bit of tissue like Kleenex. Clean threads, nut, washer, cly base area well. Smear sealant over all threads, stud & nut, both sides of washer & put some on cyl base casting. Tighten nut as normal. Quickly wipe all excess sealant well with tissue or the like. Cure minimum 24hrs. I've sealed many like this, none have leaked yet. Often the nuts may leak bad, but gasket just seeps, so this fix is acceptable.

Silicon based sealants would work too, but I've found over the years silicon can allow/encourage gaskets to migrate out. I've gotten a little gun shy with silicon on gaskets over the years. Many have good results with silicon though. Permatex Ultra Grey is one of silicon which I would use on gaskets if I used silicon. It is good metal to metal for sure. The gray tends to blend with alloy color well so it makes a clean looking joint. Generally silicon seals better if assembled while sealant is still tacky & not skinned over. I find once tube is opened, if not used fairly promptly it doesn't seem to cure properly, can leak. Most all silicon sealants do this.

So my feeling is use sealant on Cov seal even though they don't recommend.

Regarding PRT seal crush. If all is factory gaskets, seals, no head skimming, the crush just works out properly. Back in the day we didn't know about crush. We just installed seals & put on head. Always used genuine parts. Every original I took apart was the same seals. Once head is skimmed or non factory gaskets things change. Now, I 100% of time check crush no matter what. I've found even .015" crush is enough. The wedding band should fit snug on PRT so it doesn't migrate up over time. You can center punch around PRT base if band is loose. Some (many) T140 PRT were too skinny allowing bands to migrate up. For sure over squish of silicon seal will bend head, so check the squish in every case.


Probably the single most important thing is deburr & smooth head bore where PRT seal goes & outside edge of tappet block. Micro tears of O-rings will leak sooner rather than later. Rough surfaces will guarantee leaks.

Always use viton O-rings on the PRT itself both ends. The square one is silicon & soft. This is for the '69 & later PRT like you have. Interesting, the latest T140 eliminated the lower white silicon ring & just used the two rings on PRT. The wedding bad was cosmetic, only cover the gap where the silicon ring used to be.


I've been using Mercedes sealant or 510 on copper head gaskets also. Hmmm no seeps since. Of course if head is warped or bent no sealant will help.
Don

Are you sure about that? Around ca 1980 they deleted the lower O-ring and re-introduced the square section ring, pre-69 style, but as I recall, with the wedding band. The tappet guide blocks were altered to suit, without the stepped section for the O-ring.

Hi Stein, No I'm not sure about that as I have not personally assembled one with this system. A fellow club member has one & resealed top end & was discussing it. He told me it just used the round o-ring. Attempting to install square ring squish didn't work out at all & was not able to use ring. The head had been off prior with head gasket leaks & bike has unkown history, but looks stock. As I recall head was skimmed this time & no leaks. Parts book shows no square silicon ring.

I hope to see him Feb. 23rd, on club Delta ride. I'll try to get a clarification on that.

Maybe a member here that has this late bike can clarify exactly what they have. I hope so.
Don

...I did this sealing process in the 79 the week previously to the crash and followed the 79 parts book I ordered the 2 O rings that go inside the tubes and the square one that goes around the tappet block that the wedding band hold it; so all the stuff is used in the 79 models.

Yes that's correct. I'm not sure when the alteration was made, but all 79 models I've worked on were like that. Feked list the new parts as 79 on. Maybe the change was implemented during the year, but more likely after August for the 1980 season. Healy will know. My Harris Bonneville used the later system.
Although I always thought the O-ring system seemed superior, to be honest it doesn't work any better, or worse, than any of the other systems Triumph used, in my experience.
Careful assembly with attention to detail, as described so well by Don, is paramount. Once you get it right, it will stay oil tight for years or even decades.

Side bar:
I've toyed with the idea of altering the PRT system by boring out the recess in the head and inserting a piece of aluminum pipe that would spigot inside a new design PRT.
This pipe would either be welded in, or flanged and pressed in, or any other way that would keep it oil tight..
At the other end one could use a piece of pipe crimped or welded on to the tappet guide block, into which the PRT would go.
One of the problems would be the PRT angle, there would need to be an amount of play in the system to allow for this. I'd use O-rings on either end. Flexible PRTs could be used too.
With this design, the need to measure PRT seal crush and the issues with that, would simply vanish.
This isn't "a brilliant new idea", it's a system used on many designs since forever on machinery, including bike engines, or on mundane things like drain pipes etc.
Shouldn't be too hard to do either, if I could find the time.

...are not the HDs like that?
but I do not think that is values all the hassles; I mean, you need to let there some kind of play for the head crush; with that just prove that is not worth.

Sorry Fernando but you lost me with the second sentence...? Do you mean it wouldn't be worth the hassle to do the modification, compared to checking the Push Rod Tube seal crush?
If that's what you meant, I agree I suppose that's why I haven't done it!

But someday I will, just because I want to!
Possibly on the same engine I'm going to weld the rocker boxes on to the head, and cut an opening in them to assemble the valve gear.
Triumph cast the 3T head that way, can't see why it shouldn't work on the bigger twins?

Worth the hassle? Yes, if you do it for fun and to prove something, however insignificant it may be!

...Stein I mean that you need to let that play if not you cannot obtain the right distance crush so is pointless because the sealing would be no better than with the O rings.
The oil will leaks between the part and the tube.