BritBike Forum logo
BritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorBritBike SponsorThe Bonneville ShopBritBike Sponsor
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
ShoutChat Box
Comment Guidelines: Do post respectful and insightful comments.
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
johnnyrvf
johnnyrvf
Dordogne, SW France
Posts: 721
Joined: August 2006
Show All Member Profiles 
Newest Members
Psychorider, Shedengineering, Shayne Brown, Snow's Cycles, Scottboy
10858 Registered Users
Top Posters(30 Days)
franko 167
reverb 61
NickL 52
Popular Topics(Views)
1,003,127 mail-order LSR
a word from..
Forum Statistics
Forums34
Topics67,684
Posts679,548
Members10,858
Most Online14,755
May 5th, 2019
Who's Online Now
52 registered members (998John), 288 guests, and 835 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
T140 head stud leaking #784334 09/15/19 8:28 am
Joined: Sep 2019
Posts: 3
D
Devon Dave Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
D
Joined: Sep 2019
Posts: 3
My first post here so a quick 'Hi' to everyone smile
I got my '77 T140 last year and have done quite a bit of work to her already including a frame swap!
I have had a few engine related problems; faulty ignition switch - pushrod tube leaks - wrong needle jet fitted to one carb to name but a few.......
Latterly I have been fighting with some top end oil leaks which appeared since I resolved the pushrod tube leaks.
She is fitted with a 10-stud splayed head and when I refitted the head I annealed the existing copper head gasket and fitted new copper gaskets to the rocker boxes, which turned out to be a big (oily) mistake!
I have now gone back to standard gaskets which has eliminated the worst of the leaks, but I still have a slight leak which seems to be coming from the front center head stud which I am a bit confused about.
As I see it, the oil from the head can only return through the pushrod tubes so I don't see how I could be getting oil coming up through this stud? I am planning on changing to a composite head gasket as my next step.

I would appreciate any thoughts on this from the 'seasoned' Triumph experts of this forum smile

Thank you in advance for your thoughts.....

Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK
British motorcycles on e-Bay North America
Re: T140 head stud leaking [Re: Devon Dave] #784335 09/15/19 9:02 am
Joined: Dec 2004
Posts: 10,050
kommando Offline
BritBike Forum member
Offline
BritBike Forum member
Joined: Dec 2004
Posts: 10,050
Hang fire on the composite gasket, they do seal better but if they fail its a complete failure. There are special washers that seal under the nut head and stop this stud leak. Read this for more info.

http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=672820

You will need to review the area where the washer will seat on the head in case the previous too small washer has been used and raised a divot, this needs to be flat.

Re: T140 head stud leaking [Re: Devon Dave] #784346 09/15/19 3:59 pm
Joined: Jan 2004
Posts: 4,212
D
DMadigan Online Content
BritBike Forum member
Online Content
BritBike Forum member
D
Joined: Jan 2004
Posts: 4,212
Copper gaskets have to be annealed, once you bend them even a little they are not. They need a dead flat surface as Kommando referred to.
Look closely at the head/rockerbox arrangement. The head is held by socket bolts and the rockerbox bolts are screwed into the top of these. There is a gap between the top of the socket bolt and the rockerbox bolt exposed to oil and crankcase pressures.

Re: T140 head stud leaking [Re: Devon Dave] #784353 09/15/19 4:50 pm
Joined: Sep 2008
Posts: 1,120
S
Stein Roger Offline
BritBike Forum member
Offline
BritBike Forum member
S
Joined: Sep 2008
Posts: 1,120
I like copper rocker box gaskets on earlier engines, but they can be a pain to seal, annealed or not. On a T140/TR7 the standard gaskets work just fine as they don't have to endure such high loads as on the older twins and the Trident. Leakage from the inside R/B studs is a well known problem, caused by too small washers and failure to follow a proper re-torque regime after start up. The composite head gasket is highly compressible and I've even had one blow out very soon after start up.
Copper head gaskets won't compress as much but are equally important to re-torque or they can be prone to small leaks, especially between the cylinders.

Re: T140 head stud leaking [Re: Devon Dave] #784362 09/15/19 6:47 pm
Joined: Sep 2019
Posts: 3
D
Devon Dave Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
D
Joined: Sep 2019
Posts: 3
Thanks to all for your replies. I clearly have some homework to do now. Thanks Kommando for the advice about the composite gasket, I'll stick with the copper head gasket for now.
I have re-torqued the head bolts after the first startup but might well check this again. The stud that is leaking is outside of the RB covers, so maybe I still have a leak from the new gasket. I did flatten the base of the RB covers using some fine wet & dry on a sheet of glass.
I'll check out the other thread regarding the stud leaks.

Thanks again, I'll endeavor to update this thread with any progress.........

Re: T140 head stud leaking [Re: Devon Dave] #784401 09/15/19 11:15 pm
Joined: Jan 2017
Posts: 809
T
TR7RVMan Offline
BritBike Forum member
Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 809
Hi Devon Dave, I only have personal experience with solid copper head gaskets.

I am very familiar with what you speak of. Oil looking liquid seeping from center studs. This can happen on both 9 & 10 bolt heads, but 10 bolt is much more common. At
center studs. This is what I'll call condensed oil or combustion by products that resembles oil. As you say no connection with oil in rocker box area.

It is from small head gasket leaks into combustion chamber. No nearly enough (yet) to cause low compression or actually be a fully blown head gasket.
This is very common on the 10 bolt head. It is the same basic thing as when head gasket seeps what looks like oil around the sides of head where there is clearly no oil source from inside of motor such as rocker boxes or head nuts inside rocker boxes.

This is almost always caused by non flat surface of head and/or cyl top. It push rod tube seal crush is too much the PRT can raise or bend head. I've found the flatter the head & cly the less the leak.

Also annealing old head gasket may or may not work. If the old gasket is not perfectly flat meaning dips or high spots in thickness it will seep or leak even after annealing.
same with new head gaskets. They must be flat. The copper gasket doesn't compress much at all so don't expect it to help uneven surfaces.

The head & top of cyl must be checked with a straight edge for flatness & low spots. So you must check ever last square inch of head & cly surface to make sure you don't have high or low spots.

TheT140 motor has a very narrow sealing surface at the center 2 studs, which is made even worse after an overbore. The larger the oversize the more critical the sealing surfaces become.

So your next step is check head & cly. flatness. Then depending on what you find will lead to next step. I know many will throw stones at me, but often the head will need to be skimmed the very least amount to flatten it. If head it bent, it will need to be straightened first.

I would most strongly recommend new head gasket also, not reusing old one. I know many anneal & reuse them, but most I've seen that do that have seeping around head gasket. Just what I've seen.

From what I've observed most seeping heads are not bent, but have low spots hear the stud holes. Skimming must be done. Thicker head gaskets are available.

Using sealants on copper head gasket is very advisable. The sealant is up to debate. I use Mercedes 001 989 21 10. Just my choice from good results. (this works unbelievably well on cyl base & rocker box gaskets also).

However if surfaces & gasket are not flat even this sealant won't help. NONE WILL.

I try to get surfaces flat to where .0005" feeler blade is trapped under straight edge. A real straight edge, not a steel ruler. .001 may or may not seep. Any erosion of metal around edge of the stud holes is certain to cause leaks on the center studs.

Saying all this it often proves nearly impossible to keep 100% of leakage off the front center stud. Not really a seep but a trace of "sweating" of oil will often start over time. Doesn't seem to effect operation of motor or make gasket blow.

Of course head torque & retorque at specified times is critical.

Regarding the composite head gasket, I don't have any personal experience. All the later bikes I know of have been switched to copper. The one full restore that wasn't copper soon blew across front center stud & it was replaced with copper & was good. Required skimming as did mine as alloy was eroded across the hole to combustion chambers. Who knows how flat head was when motor was rebuilt? Bike came "restored".
Don


1973 Tiger 750
Re: T140 head stud leaking [Re: Devon Dave] #784402 09/15/19 11:38 pm
Joined: Jan 2014
Posts: 2,666
R
reverb Online Content
BritBike Forum member
Online Content
BritBike Forum member
R
Joined: Jan 2014
Posts: 2,666
...hello; do not forget that the torque wrench is an important tool; I mean; those "needle" type old torque wrenches do not work; plenty of failures and twisted aluminum heads due to those.

Do not know why the composite gasket could not work; all the cars have composite ones; yes; more bolts; more space, more everything but nobody think to return to copper ones.
If you do what the manual says with the composite; do not thing why would be prong to failure.
I do not see any advantage in copper gaskets; in my 500 pre unit I needed to change to copper rings like the VW bug; years ago, due to many failures with the normal gasket. In this 79, I have a copper gasket; some 3000km ago or so I dismantled the top end to cure the leaking that PO had but now I check periodically the gasket and couple of times I had a mist of oil; so I do not know if these copper gaskets are better than the composite.

Re: T140 head stud leaking [Re: Devon Dave] #784452 09/16/19 8:47 am
Joined: Sep 2019
Posts: 3
D
Devon Dave Offline OP
BritBike Forum member
OP Offline
BritBike Forum member
D
Joined: Sep 2019
Posts: 3
Thanks for the extra info.
TR7RVMan; this all makes sense. I did check the head for flatness when I changed the PRT seals, but only with the edge of a steel rule. I didn't however check the cylinder top.
I ended up using the thinnest available crush washer for the PRT's.
I checked the availability of the Mercedes 001 989 21 10 sealant that you mentioned but couldn't find it listed anywhere. I might try the 'Permatex Copper spray a gasket'.
The motor had a full rebuild prior to purchase with a new crank and re-bore, so as you suggest, this might actually have worsened the problem!

reverb; my very first trade was a car mechanic (fitter frown ) and I have always avoided these torsion bar type torque wrenches, so I think this is very good advice! I agree that theoretically a composite gasket should be better, hence I was going to try one next, but the general consensus does seem to suggest that overall a copper head gasket is less problematic.

My initial plan now is to simply re-torque the head bolts / studs to see if this has any effect on the issue. If it doesn't improve I will remove the head again and check for flatness of the cylinder top and head. I do have a spare new copper head gasket, although I am also considering getting a thicker head gasket (0.080") to lower the compression slightly with thicker crush washers for the PRT's to suit.

Re: T140 head stud leaking [Re: Devon Dave] #784488 09/16/19 5:40 pm
Joined: Jan 2014
Posts: 2,666
R
reverb Online Content
BritBike Forum member
Online Content
BritBike Forum member
R
Joined: Jan 2014
Posts: 2,666
...hi Dave; possibly you did all these: I have two 79 engines; in one I have all studs (I have nuts there instead of the bolts) so I put balls under in each one, then those famous thicker washers and the middle thick tab (under 9 and 10)
Is incredible how "light" is the torque with these heads. You always think that will blow out the gasket...
I think the general consensus is due to more baby sitting than the other and that you need to buy new ones...some people are cheap. Also that decades of using the copper ones.
Yes; if the torque wrench is not enough precise, the 5/16 studs and the others would finish with similar torque and that is not good regarding gasket.

Re: T140 head stud leaking [Re: Devon Dave] #784639 09/18/19 1:30 am
Joined: Jan 2017
Posts: 809
T
TR7RVMan Offline
BritBike Forum member
Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 809
Hi Devon Dave, Sorry, the MB sealant # is actually 001 989 89 20 10. It must be gotten from Mercedes dealer. They usually have to order it. It really works good though.

Regarding .080" copper gaskets, they work quite well. They seal well & last well. I've had one in my bike for 20k miles now. I've been involved in installing 3 of these now. It will lower compression about 20#. It of course modifies the squish band, but in real life greatly reduces pinging. 7.4 pistons are a really good thing for T140s with my fuel.

As you say, retorque & evaluate is the first step. Might just do the trick...

Regarding PRT lower square seal crush, it can be as low as .013-.015" & still work perfectly. The important factor is having smooth bore in head & smooth/debur outer surface of tappet block where PRT round o-ring slides over. Also no spit/peeling chrome inside PRT or outside at top of PRT. A thin smear of silicon on round rings I always do also.

Tappet block O-rings are prone to leak also. Again deburr, smooth bore in cyl. & groove on tappet block. I don't use sealant here, but I use a thin smear of grease on ring, bore & outer surface of tappet block. Grease helps ease driving block in also. Always use Viton round O-rings on blocks & tubes. The bottom square is silicon of course.
Don


1973 Tiger 750
Re: T140 head stud leaking [Re: TR7RVMan] #784717 09/18/19 8:54 pm
Joined: Sep 2008
Posts: 1,120
S
Stein Roger Offline
BritBike Forum member
Offline
BritBike Forum member
S
Joined: Sep 2008
Posts: 1,120
Originally Posted by TR7RVMan
Hi Devon Dave, I only have personal experience with solid copper head gaskets.

I am very familiar with what you speak of. Oil looking liquid seeping from center studs. This can happen on both 9 & 10 bolt heads, but 10 bolt is much more common. At
center studs. This is what I'll call condensed oil or combustion by products that resembles oil. As you say no connection with oil in rocker box area.

It is from small head gasket leaks into combustion chamber. No nearly enough (yet) to cause low compression or actually be a fully blown head gasket.
This is very common on the 10 bolt head. It is the same basic thing as when head gasket seeps what looks like oil around the sides of head where there is clearly no oil source from inside of motor such as rocker boxes or head nuts inside rocker boxes.

Don


Don, I usually agree with you but not this time.
True, the head gasket is prone to seepage but the substance you see is more often than not oil collected in the annulus between the stud and the bore. It's a well known fact that Triumph used too small washers under the 4 center head nuts, the ones inside the rocker boxes. The washers would dig into the head, especially on the exhaust side, thus releasing tension on the studs. The divot produced by this process would let oil seep by, and with the lost tension the gasket will let oil seep into the cylinder on the intake stroke and it will smoke. Or leak to the outside, or, commonly, both.
The easy fix is to use the same washers as on the outside head bolts, and of course mill the seating areas flat again. I do this on every single TR7/T140 head I overhaul, I've never seen one that wasn't affected to some degree. In some cases I need to use a sealant to stop it completely. John Healy says he has produced a special washer with a built in seal to combat this, so I'm not making it up....

SR

Re: T140 head stud leaking [Re: Devon Dave] #784743 09/19/19 2:33 am
Joined: Jan 2017
Posts: 809
T
TR7RVMan Offline
BritBike Forum member
Offline
BritBike Forum member
T
Joined: Jan 2017
Posts: 809
Hi Stein Roger, Yes we see this differently. That's ok. I'll not try to convince you so don't take it that way. I know you are a skilled technician with a lot of experience. I have great respect for your point of view.

My view is the metal between cyl bore & the groove in top of bore should seal compression so combustion gas cannot enter the stud area, and oil cannot enter combustion chamber, if the seal is good.

Triumphs being what they are, many things are not good. However if both cyl, head, and gasket are flat it hardly leaks at all, just the most tiny seep. I mean if you see actual liquid at head gasket outer bolts or center studs the head gasket is compromised do a lessor or greater degree. If oil can drain down the four 3/8 studs & enter the combustion chamber enough to cause oil consumption or smoke the head gasket is basically blown in that area. In this case I would expect there is a low spot in the head next to stud hole. This calls for a skim removing the very least metal as possible to achieve flat surface. A skilled machinist can remove as little as .004".

When my head gasket blew across front center stud 3000 miles from new, it eroded the alloy enough where they had to take off .009" to get it flat. 34 years later at 12k miles the tappet block o-ring split. I checked head for flatness. Was good within .0007" & no dips I could find. I didn't have a .0005 feeler at the time.

I've seen the 4 studs full of oil several times & have observed no leakage into combustion chamber or to outside of head gasket. This tells me the head gasket is sealing good around the studs.

I've found copper coat sealant better than nothing or grease, but the Mercedes sealant has proven very effective at reducing the seeps to a bare minimum. In 5k miles without wiping joint surfaces there is no liquid oil visible. However, the head & cyl top must be very flat with no dips. If sealing surfaces or head gasket are compromised the Mercedes sealant will leak. No sealant or gasket will cure compromised sealing surfaces.

That is my experience & take on it. Again, different points of view which I respect.

That's a good part of this forum is discussing different points of view which has often greatly expanded my skills & knowledge.
Don


1973 Tiger 750

Moderated by  John Healy 

Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.3