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Oil leaks from sump bolts


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As we know the two sump bolts at the front and the two at the back go into alloy. The ones on my car can no longer be tensioned up. I've put helicoils in but still can't tension up 3 of them.

The leaks are just a drip or two on the floor of the garage but I was going to have a full thread repair done. I contacted a recommended thread repair business. He wants the car on a hoist and says it will take him quite a few hours and he can't guarantee the repair.

I decided to persevere with the leaks, it is a TR and the engine does have a few other minor leaks. But I'm having 2nd thoughts.

Any advice on the job and the degree of difficulty in getting a 100% result?

 

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Hi John,

Mine is not leaking, I installed the steel bridge-block. It’s not only the block, also the perfect fitting of the wedges and the use of a silicone sealant that are important.

Waldi

 

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lived with these leaks for a fair few years before the engine was rebuilt.. Only thing I had to remember was to not park the TR on my mother-in-law's block paved drive!:D

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John, I’m with Waldi on this one, use a decent sealant with a new gasket, I’ve just had the sump off and it went back fine. The threads are known for stripping so go with recommended torque setting as much as possible, the sealant will ‘help’ the weaker threads.  All of that said, if you can stop a TR leaking you are either a genius, a magician or a liar.

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1 hour ago, John McCormack said:

As we know the two sump bolts at the front and the two at the back go into alloy. The ones on my car can no longer be tensioned up. I've put helicoils in but still can't tension up 3 of them.

The leaks are just a drip or two on the floor of the garage but I was going to have a full thread repair done. I contacted a recommended thread repair business. He wants the car on a hoist and says it will take him quite a few hours and he can't guarantee the repair.

I decided to persevere with the leaks, it is a TR and the engine does have a few other minor leaks. But I'm having 2nd thoughts.

Any advice on the job and the degree of difficulty in getting a 100% result?

 

TR GB here in the UK can supply that block made out of steel and not Monkey metal. That is what I have fitted and have no leaks! I my view the only way to stop the leaks from the monkey metal is to fit bushed inserts. But that involves quite a bit of  m/c shop work. UNC helicoils also would be a better option instead of UNF? I was always taught that you use course threads only in soft metals?

Bruce.

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Hello,
on newly made engines and when I have to go to an oil pan I always use stud bolts
in the aluminum bridge at the front and back.
However, I glue them with Loctite. At the front, no more oil is guaranteed to come through the thread from above.
Tearing of the thread is almost impossible. (With enough strength, some can do it too)
And assembly upside down is much easier.
Nothing slips anymore.

regards
Ralf

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Hi Ralf

Like the stud idea what size do I need?

Cheers 

Andy

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11 hours ago, John McCormack said:

As we know the two sump bolts at the front and the two at the back go into alloy. The ones on my car can no longer be tensioned up. I've put helicoils in but still can't tension up 3 of them.

The leaks are just a drip or two on the floor of the garage but I was going to have a full thread repair done. I contacted a recommended thread repair business. He wants the car on a hoist and says it will take him quite a few hours and he can't guarantee the repair.

I decided to persevere with the leaks, it is a TR and the engine does have a few other minor leaks. But I'm having 2nd thoughts.

Any advice on the job and the degree of difficulty in getting a 100% result?

 

Maybe put studs in with Loctite 271 ? I went for a roadworthy in order to switch to club plates yesterday and got a fail due to an engine oil leak, even there was no visible drip on a new section of concrete driveway when the car was left there overnight, the Victorian authorities are much less forgiving on leaks than they were 20-30 years ago. You  might have to fix the leak eventually.

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hmmm, Loctite 243 is medium,

glues faster than the 242 I used for medium issues,

also can seal leaks (I always thought all Loctite products seal?) and is tolerant to some oil contamination.

My 242 is empty so yesterday I order 50 ml bottle Loctite 243.

Any advice from Ralf is welcome

Ciao, Marco

edit: for this issue 271 or 272 could be the correct product

Edited by Z320
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I have some blocks from steel for the front made from a clubmate.

Jigsaw does them also for a good price.

That stiffens the front block and allen heads can be used for proper fixing.

If old block needs new thread be aware that the debris may pop into the engine

although most will pop out from gravitation.

 

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If sump bolts, especially those in the alloy bridge, strip their threads, then they have been overtightened, no doubt by the DPO.    The same abuse 'bells' the bolt holes in the sump flange, by crushing the gasket material around them.      Thereafter, it's impossible to compress the line of the gasket, as the metal gets in the way, and so leaks continue.      It's necessary to straight-edge your flange and dress back the belling on a suitable stake.   And then observe the correct torque on these bolts, 16-18 lbs-ft, when 'hand tight' is about 12 lbs-ft.

John 

Pic 1.JPG

Edited by john.r.davies
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On 10/22/2020 at 10:30 PM, astontr6 said:

TR GB here in the UK can supply that block made out of steel and not Monkey metal. That is what I have fitted and have no leaks! I my view the only way to stop the leaks from the monkey metal is to fit bushed inserts. But that involves quite a bit of  m/c shop work. UNC helicoils also would be a better option instead of UNF? I was always taught that you use course threads only in soft metals?

Bruce.

I have read that the UNC thread doesn't 'grip' as well as UNF and that is why Leyland used UNF. As the lesser of two evils I guess.

The engine is very good so I won't be doing anything major for a few drips of oil. At the next oil change I'll drop the sump and locktight some studs in. Then refit with more sealant.

Edited by John McCormack
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My sump pan was like Jihn shows on his photo.

So I pressed the bended flange flat with a bolt, nur and a socket 13 mm x 1/4"

Anytime there has been cork seals on the market, I found one NOS on eBay some years ago.

I use it with the bolts not tightened too much.

To be honest: it leaks less but anyway

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I like the idea of studs for the front and rear sump fixings into alloy and will make this mod when the sump is next off. Another benefit of course is that it will make it a doddle to locate the sump when replacing.

Tim   

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10 hours ago, John McCormack said:

I have read that the UNC thread doesn't 'grip' as well as UNF and that is why Leyland used UNF. As the lesser of two evils I guess.

The engine is very good so I won't be doing anything major for a few drips of oil. At the next oil change I'll drop the sump and locktight some studs in. Then refit with more sealant.

The metal that BL used is Zinc alloy it is not alum. It is known in the UK as Monkey metal because of its poor tensile strength when threaded and easierly fractures. The only way in my view to guarantee a good thread is to use  M/S top hat inserted bushes in Zinc alloy that can be done up very tightly if required  and you can use UNF threads without the problem of pull out. Also remember that the original threads were probably cast and that is another reason that they disintegrate. All done for cheapness in production?  That's why the TR GB is a good alternative in steel, its fit and forget!

Bruce

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26 minutes ago, astontr6 said:

the original threads were probably cast

How do you do that unless lost wax or some similarly expensive method? I doubt that was the method. Let's not diss the designers out of hand. More likely various owners have overtightened. Having said that, I'm about to fit a steel front bridge from Goodparts. I have already helicoiled the threads, and they hold just fine, but belt & braces. BTW if you helicoil a UNF thread, you get closer to UNC in the alloy while maintaining the original thread for the bolt. But as JRD says, sticking to the designed torque is the secret.

JC

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1 hour ago, JohnC said:

How do you do that unless lost wax or some similarly expensive method? I doubt that was the method. Let's not diss the designers out of hand. More likely various owners have overtightened. Having said that, I'm about to fit a steel front bridge from Goodparts. I have already helicoiled the threads, and they hold just fine, but belt & braces. BTW if you helicoil a UNF thread, you get closer to UNC in the alloy while maintaining the original thread for the bolt. But as JRD says, sticking to the designed torque is the secret.

JC

It is not lost wax process? it is pressure die mould process as use on the TR rear lights surrounds.

Bruce.

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I was surprised to read that the OE bridge piece was made of 'pot metal', which I always associated with cheap model cars or trim.    So I went to find out.

I measured the volume of a spare bridge piece, by dropping it into a container of water and abstracting water to return the level to the original.   It has a volume of 40mls, and weighs 245grams, so has a density of 6.125gms/cm^3.     This is three times the density of any aluminium alloy, but much less than steel.    According to the Wiki, the density of Zamak is 6.6, but as "Pot metal" is not a specific alloy, I think the case is proved!   This must be a Zinc alloy, but with more aluminium that in actual Zamak.

This method can't determine how the threads in this part are formed, but as that was said by Bruce, whose pot metal allegation I tested, I must believe that as well!

John

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Fair enough. I would like to understand how a moulding process can produce internal threads though. And I mean it - any reading material gratefully received. 

JC

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Internal threads can be cast, but it requires a complex and expensive mold that has hydraulic actuators that unscrew male parts of the mold.  Molding of plastic bottle caps is related, but these are very course pitch, and much larger.  I'm not sure the technique would even be practical for smaller fine threads.

Zamak, aka Mazak or pot metal, is noticeably heavier than aluminum. It's usually easy to tell them apart by feel with a chunky part like the sealing block.  For more complex shapes, a drop of muriatic acid will fizz on Zamak, but not on aluminum.

Ed

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When mine was a daily driver year-round I reckon the leaked oil saved the  central chassis from serious rot.

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