Chain tensioner gallery question

[LateApex]

I had an oil leak from my manual chain tensioner.  There is a crush washer but it does not seal.  The problem is the area where the tensioner contacts the rail fills with oil, which then drips out the end of the tube.  I was thinking that I could drill a drainage hole in the bottom of the area (see red dot in pic) that would allow the oil to drain back into the crankcase once the engine stops.  I think the tensioner would still get an oil bath  from oil flying around behind the timing cover.  

 

Does anyone see a problem with this concept? 

[tech71]

23 minutes ago, LateApex said:

Does anyone see a problem with this concept?

With a manual tensioner I suppose not but you are screwing yourself and others later if its desired to reinstall an OE hydraulic tensioner.

Seems kind of backassward, cant be that hard to get a correct crush washer and fix at the source, stick a small  o ring under the threaded shaft jam nut, thats probably where its leaking

Edited June 30, 2023 by tech71

[tech71]

10 minutes ago, LateApex said:

The problem is the area where the tensioner contacts the rail fills with oil

Its supposed to do that

[tzei]

Yea try to fix the seal. Drain hole - no no.

 

btw that’s one helluwa skimmed cover u got there.

Are you sure it is not coming from that welded part? Looks moist. Or somewhere upstream? There are lots of places it could seep a little.

[LateApex]

36 minutes ago, tech71 said:

 stick a small  o ring under the threaded shaft jam nut, thats probably where its leaking

 

This makes sense - never thought of that.  Thanks.

[jimk]

Since the tensioner and tensioner shoe is on the slack side of the chain (that is never under tension), somebody explain why the manual tensioner in the first place.

 

Seems like a long time ago someone didn't understand the tensioner system and thought this was a solution to a problem that doesn't exist.

[LateApex]

3 hours ago, jimk said:

Since the tensioner and tensioner shoe is on the slack side of the chain (that is never under tension), somebody explain why the manual tensioner in the first place.

 

Seems like a long time ago someone didn't understand the tensioner system and thought this was a solution to a problem that doesn't exist.

 

Rotating assembly assisted deceleration, common in racing situations, often at high RPMs, will put tension on the "slack" side of the chain.  With high compression pistons and a high lift cam, you do not want changes in cam timing that could be caused by the hydraulic tensioner yielding.  

[Son of Marty]

Mr Apex is right on, this is why you commonly see dimples on the exhaust side of the pistons.

Edited July 1, 2023 by Son of Marty

[jimk]

How can the rotational inertia of the  cam and valve spring load be greater the rotational inertia of the crankshaft/flywheel/clutch assembly?  That would be the only time the cam rpm would turn down slower than the lower end rotating rpm.

Seems more likely that exhaust indentations in piston tops is caused by late valve timing caused by worn chain, centers distance between the cam/crankshaft reduced from head shaving/block decking.

I think it's more an issue of "I gotta have one of those" than rational thought about the tensioner.

Edited July 1, 2023 by jimk

[TobyB]

In the world of racing, you rule out everything you possibly can.

Thus, jamming the (intelligent, well- thought- out, very reliable) tensioner rules it

out as a possible cause of trouble.  There IS a lot of dynamic loading on a 

4 cylinder cam, and I can see why an 8500 rpm race motor with a 14mm lift cam would do this.

When it doesn't cost anything, and might save a weekend.  ANY slack in the chain

can let it really whip around.

 

My 7500 motors all ran hydraulic tensioners, 12mm of lift, and I never had a problem with them.

 

OP, your front cover has been sanded- and from that one pic, it looks like the 

edge nearest us-

where it mates the block-

has been radiused downward.  That's going to leak like a SOB.

Use more black RTV, and the stock crush washer on the tensioner, and maybe a little

RTV on the washer, too, just for good luck.  I'd also be inspecting the end of the tube-

a nick or dent there makes for a pretty good leak.

 

t

hydraulically dampened since 1968

[Cabbage Fumes]

I use mechanical tensioners, and I drill a drain hole in the valley so I never get oil weeping around the threads.  My blocks are decked with the front cover and will never see street duty. And no, as much as I like the design, I wouldn't bet my life on a hydo keeping enough tension on a high rpm decel.

[Cabbage Fumes]

As far as the OP's issue, before I started drilling drain holes, oil would always weep past the threads and down the side of the block and pan. The key is when assembling it, make the center adjuster perfectly clean, and work Dirko into the threads. Before it cures, set the tension, tighten the lock nut. It won't leak.