• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

Torqueing the head, to cure a rear crank leak?

Share this page

B

bunzil

Jedi Trainee
Country flag
Offline
Thanks to Paul in Rhode Island for steering me on this one....

I bought my TR6 in '84 with 19k miles on the clock and it always had a small leak from the rear crank; one certainly not worth breaking down to fix. There was also a small pool of oil at the very back of the head, which collected on the block at the bellhousing. While I cleaned it from time to time, I never really paid much attention to this leak...it was so, small!

Last summer, after a dialogue here, I traded to 10-40 oil from 20-50, and at the same time removed the remaining pollution equipment. The pool of oil on the block seemed to increase as a result which, at the time, I attributed to the engine hoisting screws. That turned out not to be the case. Two weeks ago, after much searching, I finally saw a leak coming from the very back of the head.

Figuring "why not?", and one step away from replacing the head gasket, I retorqued the head. Indeed, some of the nuts seemed a bit, er, loose. Afterwards, a test drive revealed,'lo and behold, that not only did the head leak vanish, but the leak at the crank as well - which indicates it wasn't a crank leak at all over all this time, but a slow drip from the head coming down the side of the block.

I feel very lucky for such an easy fix. It usually turns out for the worse. But the once again moral of the story is: check the obvious. So if any of you have a rear crank leak, with some oil collecting behind the head, torque the head!!

PS - Indeed, the leak was exacerbated by the lighter oil. But I still stand by the cold start benefits associated with same for less frequently driven, cold weather cars.
 
I'm following your tip as soon as the Sat & Sun British car cruises are over this weekend.

Films at 11:00.
 
The 'ole TR Bible said it in there somewhere; torque the head, now and again, on haphazardly picked, randomly odd numbered days. Who would have figured they meant it?
 
Ned, what exactly do you mean by re-torquing the head? I'm guessing just backing off the head bolts and then re-setting at the factory torque? How many are there? I've never done this before and I do have the same symptoms you had.

Reid
 
Reid,

That's precisely what I mean. There are 14 bolts holding the head down and starting in the center, loosen each 1/4 to 1/2 turn, and then torque em back down, alternating outwards as you go - the manual describes the procedure. The manual says between 60 and 80 lbs, I did 75.

You will need to remove the rocker arm assembly to get to the left bank of bolts. But this is an easy exercise. I do suggest you re-adjust the valves after you put it all back on. This is easy as well, and if you've never done it before, might take a few attempts with small adjustments to get the tappet noise to your liking.

The retorqueing might not work. But as they say, "it can't hurt." And costs nothing to try.

Good luck
 
As I read the thread topic line I thought: "Sure... I'd have a tooth pulled to relieve HEMORRHOID pain, or apply a torniquet to the neck to stem a bleeding head wound, too..."

Many folk do overlook the fact that fluids will find the path of least resistance to get to being the puddle on the floor. Same can be said of coolant. Not always obvious on first inspection just where it may be originating. Good rule of thumb is to cure the "highest" one first. Clean everything well then go for a nice long run before you look again. /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
I've seen other cars have the same problem with oil leakeage out a cyl. head. An occasional retorque never hurt anyone!
 
Two things. If you are gonna retorque your head, I would not recommend taking the torque out of the bolts before retorquing. That to me negates the whole process of stretching the bolts. It just means that you will have to re-retorque.

Also, how valid is it to retorque a 20-something-year-old head gasket. Wouldn't it be much, much better to put in a fresh gasket. That old gasket is not gonna take a lot of new torque on it without causing some inherent leaks.
 
Those gaskets are made differently than the gaskets of today. An occasional retorque is often a good preventive maintenance thing on the layered/composite gaskets.

A lot of foreign mfr's in those days recommended retorquing as part of their maintenance plan(if you look at the long term mileage accumulated)
 
Retorquing heads on imports was very popular in the 60's and 70's, but I'm not going to loosen mine. I'll try the two in the rear where its leaking and if they are loose, fine. If not, it stops there.
 
While not an engineer, I don't think it wise to retorque just a few bolts. Do 'em all. The idea, isn't it?, is for uniform pressure across the head. Loosening just a few is asking for problems elsewhere. That's why I had a leak to begin with.

I disagree with Bill above. A 20 year old seal (on anything) can sometimes - not always - be reacquired if it's loosened up and retightened. Why not try torqueing on the TR before prying the head? There is no downside.

To Bill's point, my 20 year old gasket isn't taking "a lot of new torque" but merely taking the torque it lost - Triumph says these bolts loosen.

Again, no harm in trying. If it still leaks, yank the head.
Simple logic, no?
 
Paul,

To each his own, but with the rocker assembly removed anyway,why not do them all?

While Bill is right, a new head gasket is preferable, there is no downside whatsoever to re-setting the torque on the original one, and it's a far easier job. Why skip over a potentially easier solution? If it doesn't work, go to step 2 and remove the head.

As stated by others on the forum before, you should slightly loosen the bolts first - one at a time obviously - and this seems to make sense. I suspect the reason is twofold: 1) so that you don't get a "jerky" tightening effect starting from an already tightened bolt, and thus a false reading and 2) so that you ramp up to the correct setting slowly and smoothly thereby knowing you've achieved the correct setting.
 
Ned,

I'm not disputing the proper method and sequence used to retorque the head. I'm just going to check the two rear. If they are tight and the leak persists, I'll replace the head with the one that I'm having modified at the machine shop.

But that will probably not be until the fall or winter.
 
Back
Top