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I looked at a ladies MGF yesterday for RobboMc and she needs a few parts, one being the timing belt tensioner. When did MG change over from a manual to an automatic timing belt tensioner? Rimmers also mention a 23mm & 26mm timing belt.
I only have basic details (1997 1.8i) and is over 250Km from me (hence the question). I’m trying to prepare a list of what she needs so she isn’t ripped off by exhorbitant parts prices at a specialist garage.

Given the last part of the VIN you should be able to find the correct belt and tensioner on a site like Rimmer Bros.

Can't 100% confirm re the tensioners (away from my info for a few days), but the VVC uses a manual tensioner in all its iterations, and therefore a 23mm belt rather than the later 26mm belts used with the automatic tensioner.

HTH

Hi Swampy,
Your effort to help this new MG owner is outstanding mate.

The car is almost a replica of mine, well originally anyway.
My understanding is that the automatic tensioner comes with the 26 mm belt.

Initially all 1.8 MPi cars came with the manual tensioner and 23mm belt.

My car is a 1998 model and was originally built like this. Jan's car being a 97 model is almost certainly manual/23 mm.
I cannot swear to the cut over date, however the 2000 MY cars with MEMS3 came with the auto tensioner/26 mm belt set up.

Whilst one assumes the cut-over was somewhere near or at the model changeover, there's nothing technically stopping a MEMS1.9
engine running an auto tensioner/26 mm belt so it could have been changed any time.

The only difference I'm aware of the the different location of the drill hole that the tensioner bolts into.

Do Rimmers have a model cut-over on the listing for the belt?

Unfortunately Rimmers didn’t include a VIN cut-off. As it probably is an early 1997 car (mine has a 1997 Oz compliance plate but a 1996 build), I’ll recommend the narrow timing belt and manual tensioner.

Found this buried in MGFcar.de

Rob Bell, North London Posted 30 June 2005 to the BBS
The comprehensive list of engine numbers to which the tensioner change date applies is listed below:

18K4FJ31 153993
18K4FJ32 147263

18K4FJ78 151555
18K4FJ79 153785

18K4FJ89 146503
18K4FJ90 141815

18K4FL66 148135
18K4FL67 665464

18K4KL36 118709
18K4KL37 102149
The last two engine numbers apply to the VVC engines

So assume it's a J32 with an early engine number then it's 23 mm.
My 98 build car was J32 122258. Based on the production rate of 260 cars/week
that puts the cut over SOMEWHERE around May, 2000 but anyone with a 2000MY car would need to check the engine number carefully.

I've seen several 1995 and 1996 MGFs with auto timing belt tensioners due to the cylinder head being replaced at some point in it's history. So, don't assume that it will have a manual tensioner due to the engine number.

Absolutely true Mark. My car was almost one of those, but I was lucky enough to find a new engine instead of fitting a new head..
It was a MEMS3 engine but I have a MEMS1.9 car so we 'reverse fitted' the MEMS1.9 cams.

So I have a MEMS1.9 with a MEMS3 engine number and an auto tensioner and 26mm belt.

It will be fun for someone to work that out in 30 years time. I'm sure there are plenty of hybrid F's around the world.

The only safe way is to check the width of the belt, as someone else has said if its 26 mm its also auto tension. I very nearly got caught out as my car was made in the change over period and the motor factors swore it was a 23 mm. It was a nice sunny day so I checked and yes it was a 26 mm! I get the impression anything went in the change over period.
TP