The DW tensioner is significantly different from either of the two that
Michael is referring to, and substantial more expensive than either. I did
some "research" on the web (as a scientist I struggle calling that research)
when investigating tensioners for my current rebuild and from what I can figure
out there are at least three tensioners on the market that will work. This
same tensioner fits MGBs, Jaguar XK engines and Land Rovers, and the majority
of chatter on the web is from Jag and MGB owners.
1. This is the â??baseâ?? model which is readily available and is a copy
of the original part. The web revealed a number of reports of the rubber pad
un-bonding or the whole piston popping out. I suspect the latter must be due
to a stretched chain allowing the piston to come out too far. Many of the
failures of the rubber un-bonding are from racing applications but there are a
lot from road cars as well. One English builder who races MGBs says that all
his failures were on race engines and he thinks failures on road cars are very
rare, but he is talking of MGBs. Many reports name the manufacturer as
â??Rolonâ??, although there could be more than one source of this base model.
This is the â??baseâ?? one that MOSS supplies and you can see â??Rolonâ??
stamped into the casting in their illustration. It is $13 USD
2. A French company called Renolds makes an upgraded tensioner that is
visually similar to the original but apparently has better pad material this
is the one Mike has illustrated on his post. I could only find one report of
the bonding failing on this tensioner. Reports vary, but it seems this part is
the OEM Jag replacement available from dealers as part # EAC3629. Some people
had reported getting the Rolon part supplied from Jag dealers, and one report
said both were available as OEM and â??upgradedâ?? OEM from his Jag dealer.
This is the tensioner sold by MOSS as their â??premiumâ?? tensioner. It
appears available from other sources including Jaguar dealerships. It is $90
USD.
3. The third one is described as a â??hydraulicâ?? tensioner. This is
the one sold by DW for 130 GBP. I think that A-H spares sells the same one for
90 GBP, but the difference may be the VAT. The one from DW has â??DWRâ??
stamped into it, but they may be adding that themselves. This has a nylon
slipper and it is narrower than the chain, whereas the other two have rubber
pads slightly wider than the chain. I cannot find any reports of this type
failing, but I did find a report of it being a poor fit. Oddly, the chat lines
that had extensive discussion â??Rolonâ?? vs â??Renoldsâ??, do not mention this
tensioner at all, so no information on reliability, which really means no
failures (who takes the front end apart to check the tensioner is OK?).
However, I am sure that relatively speaking, very few of these have been fitted
relative to all the Jag rebuilds using the Renolds unit and there are probably
1000s of the Rolon units running in MGBs.
Regarding them all being hydraulic, there is a bit of confusion, but several
sources say that the oil feed is just to lubricate the pad and the tension is
all provided by the spring. However the DW one is said to be truly hydraulic.
Whether oil pressures assists with tension on the first two, or dampens the
piston movement caused by oscillations of the chain, has been raised as a
question, but no definitive answer.
That is the sum total of what I know about timing chain tensioners. For the
record, I opted for Moss' "Premium" tensioner (#2 above).
Cheers, Mirek
'59 BT7
-----Original Message-----
From: Healeys <healeys-bounces@autox.team.net> On Behalf Of Bob Spidell
Sent: February 22, 2021 12:22 PM
To: healeys@autox.team.net
Subject: Re: [Healeys] Timing Chain Tensioners
I can't answer your question definitively, but can say--in hindsight--that I
wish I'd installed DWM's upgraded tensioner on my BJ8's last overhaul.
Expensive (relatively), sure, but failure of this part would be
near-catastrophic, and I've heard anecdotally that aftermarket versions have
failed (and I have an inherent distrust of any aftermarket part with rubber).
How much is (relative) peace of mind worth?
I installed DWM's flexible oil pump pipe in my BN2 on DWM's 'advice' and I'm
glad I did. I know of at least one failure of the original, metal pipe (from
someone on this list).
On 2/22/2021 9:10 AM, Michael Salter via Healeys wrote:
> I note that the usual suspects all now seem to be selling 2 grades of
> 6 cylinder timing chain tensioners.
> As far as I know the more expensive variety, which are 5 times the
> cost of the less expensive type, are relatively new on the market.
> They are apparently made in France and come in a Jaguar/ Land Rover
> package.
> These are slightly different from the originals in that there is a
> lubrication hole in the rubber pad that I don't recall seeing on any
> others that I have used.
> In my experience until very recently the rubber slippers were not a
> problem on these tensioners but wear of the piston was pretty common
> on higher milage ones.
> My question is are these "Premium " grade tensioners significantly
> better and are they worth the extra cost?
>
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