Lower chain tensioner different from original, be careful

I am rebuilding my 1970 4.2. I ordered a timing kit from one of the usuals and was appalled at the quality when I opened the box. All the stuff was made in India. The chains were not even crimped properly and the chain guides were not even at right angles. The tensioner was a very sloppy fit and in my opinion a risk to install. I decided to order new chains and an expensive Jaguar tensioner from another one of the usuals, initials TJ… The better tensioner was made in Spain and is somewhat different, so it would be easy to have a problem in the install. Here are my observations.
The first photo shows the new and old parts side by side. The old one has an orifice in the inlet and feeds oil out the rubber shoe. The new one has an orifice that feeds oil out the side of the plunger. There is still a hole in the rubber part of the shoe, but no drilling through the metal shoe support. The new one came with 2 metal plates that get clamped between the base and the block to keep the shoe from rotating, but these did not fit because of an interference with the block, I considered grinding off a corner, but thought why not use the old plate. Then I realized this would create a considerable oil leak. See photos. The new one did not include the inlet orifice. So I removed the old orifice and installed it in the new base. But now the 2 new side plates wont go over the old orifice because the hole in the plates is too small. So I reused the old plate as the orifice will make a seal in the block and not create a leak. **I see a couple of ways that installing a new lower tensioner could cause oil leaks and low oil pressure.**Not installing the old orifice for one and reusing the old plate for another. Hopefully the photos will make this clear.

Myself, I cleaned original lower chain tensioner and reinstalled. 4 years ago there was a batch of bad lower chain tensioners. For 'usual ’ upper tensioners I had to shave them to fit as they fouled head reinstall. Wish I reinstalled original chains as ’ usual ’ upper is tight, even at its least tension adjustment.

Patrick
'66 fhc

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I noticed the same thing with after market tensioners, the quality is very poor and I was reluctant to install them, not square, different thickness from original, and different durometer rubber ! I also found the new ones are not as well bonded as the originals.
It is a shame that our more reliable suppliers don’t reject this crap that India and China sends us !
The chain retaining clip is on backwards, (in your photo) turn this around to stay on in the direction of chain travel !

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Is it “Rolon” brand? They’re just awful. Like Patrick, I reused my housing, but I used the new replacement shoe. Like yours it interfered so I had to file a sliver off one side to make sure it didn’t bind.

Your shoe looks pretty worn so you might want to do likewise. I don’t think my original shoe had an oiling port in the face of the shoe. Mine is an earlier car though and I am not 100% certain it’s original to the car as the engine had been rebuilt once. Someone is free to correct me but I’m not sure that it really helps. The chain should be seeing plenty of oil without that. The place I’d want to see lubed would actually be the shoe piston.

MGBs use a nearly identical tensioner “foot”, and the Rolon brand have a terrible reputation for failure, where the vulcanizing fails, and the rubber tears off.

The hot ticket is to buy a OEM Jaguar tensioner foot, but you have to be careful as they use multiple suppliers…apparently the one you want is the one made in France.

Although I’ve never measured them to be sure they are identical, the Nissan L-Series (240z-280z, and L16-L20) engines also used a similar tensioner foot…I’d bet dollars to doughnuts they are dimensionally identical to the English parts.

You can still find OE Nissan parts, and in general, they are excellent quality…may be another source of good quality replacements.

Any idea where this hot ticket can be scored Ben? My engine might be coming apart sooner than later for a new rear seal.

I buy mine from a vintage racer/parts pusher named Basil Adams in the Bay Area…he keeps the French ones in stock.

His email is basiladams@yahoo.com

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I bought the French one for my Mk 2 last year. Came from my local Jaguar dealer - in stock! No dramas at 1000 miles. Paul

I believe that the French tensioners being referred to are by Renold. However, the research I did into the subject a while ago suggests that the Rolon brand and Renold are made by the same organisation, either in a different location, or at a different time, or both. See…

-David

The Rolon pads have the rubber ‘shoe’ clearly bonded just to the face of the metal foot, whereas on the French Jaguar parts, the rubber literally encompasses the metal foot…so, there is definitely a design/manufacturing difference between them.

There is a very experienced engine builder on mgexp.com who originally turned me onto the French Jaguar tensioners. He won’t even put the Rolon parts in his street-engines due to past failures, where the rubber simply separated from the metal, but he regularly uses the OE Jaguar tensioners in race engines that see sustained 7,000+ rpms.

I also found that Toyota used a similar tensioner but with a fatter plunger. I have an old one in the garage, I’ll dig it out and perhaps we can compare measurements.

Few years ago I took my engine apart (resleved in Pa), I found what I hope was the original lower chain tensioner; I said ‘hope’ because I reinstalled it (to avoid at that time were a batch of bad tensioners). Far as I know, block was never apart till I got it; but POs achieved several botched head gasket installs (that quickly failed) because true overheating was due to small holes in coolant head passages between (correctly repaired/welded at CW). As well as new steam holes between 3 and 4 to match block; as early 4.2 Etype lacked head steam holes to mate up to same holes in block-----long story); Not shown in pic as lifting tool covers steam holes.



!

FWIW, my 1970 U20 Datsun engine(2000cc roadster), uses the same tensioner as my 3.4 140 engine EXCEPT that Nissan did not provide a ratcheting device.

Here is the Toyota one. There is a guide plate to limit the plunger travel.

Sorry the pictures arn’t very good. Will have another go later.

Here’s a Toyota tensioner. Wonder if it would do the job.

Bolt spacing does not look correct: true, that early Datsun engines (A10/12/13/14/15, R16, U20, L13/15/16/20) used a compatible one, but likely are no more available than the Rolons.

Anyone know who the manufacture of the original part was? I can’t recall as it’s been buttoned up inside my engine for 18 years. I seem to recall it said made in GB though. Does it cross over to other cars directly? I’ll bet there are still some sitting on shelves somewhere. The question is where though.