MFI throttle body rebuild

[58A - 71E]

Then the mag air stacks were removed to get to the TBs.

The hard lines from the MFI pump to the injectors came off a lot easier than I thought with a flared spanner and some penetrating oil.

The TBs however were a real pain to get off, and in the end I had to improvise a little (well a blow torch helped) to create this helpful little tool, the nuts were 12mm and luckily I had an old spanner



Then the TBs were soon off



Here's the TBs as they came off



I couldn't believe how filthy they were, especially the butterflies, with a good couple of mils of cr*p encrusted on them.

In an earlier post John had mentioned that the screw holding the butterflies on might be tight and require drilling - well he wasnt wrong These little b*stards took some working out, but in the end I got all of them but one out with an impact driver, the other sheered off and needed an extractor to remove

[58A - 71E]

This picture unforunately didnt work too well, but when held up to the light it was obvious that the butterflies were not seating correctly in the body and light was visible past all 6 of them



So it looks like they'll need boring and oversize butterflies fitting

One of the butterflies, caked in cr*p



Clearly the culprit is the TB bushes, which will need replacing. You can see the ridge that has been worn out by the butterfly due to the play on the shaft better here



and here



(The wet stain is carb cleaner that I had blasted every where. Also visible is the other, smaller air hole to the right of the bush aperture which was completely full of cr*p))

[58A - 71E]

Not happy with my ability to clean these up I once again "improvised" for a parts washer



The wife was well pleased

Anyway what it did reveal was



worn away by butterflies

and as John mentioned earlier, the area where the return springs seat have all worn



So now to find somewhere that can do these for me...

Any suggestions

Cheers

[hot66]

superb thread

I love those little jobs that end up with the motor on the floor and the whole induction system in bits

I bet Tracy was really pleased when she opened the dishwasher to find all that in there

[johnM]

Hi

what do you want doing? just the boreing or a complete rebuild?

Kind Regards

[Alan @ CanfordClassics]

Hi,
You will probably need the T/B bushes also replacing. To retain the same sized butterflies they may need boring and then sleeving, but some just over bore them and use larger butterflies. If it is just boring you need I can get that done for you, but suggest it is better to have them overhauled completely.


HTH

Alan

[58A - 71E]

I bet Tracy was really pleased when she opened the dishwasher to find all that in there

Pleased, err, thats not the words Tracey used I think we won't go there again James


I have a set of 12 new bushes from OPC and will definitely be needing these replacing.

Is it possible to have material replaced around where the spring has worn the bodies down? If so I'll need that doing.

If they need setting up using a flow bench I will need that doing as well, which looks like I'll be needing the full rebuild

Wasn't sure what to do for the best with the bodies?

a) Bore out and fit oversize butterflies
b) Bore, sleeve and fit same size butterflies

Alan is kindly helping me out with some new Supertec rods and all the hardware is being plated at the moment, and as I say I've got the bushes, so really its sort out the best option for the bodies and have them rebuilt using the flow bench I reckon. Opinions?

Cheers

[58A - 71E]

Well they are now in the post to Kendal

Mike says he'll take a look to see if new material can actually be welded in where the return springs have worn the bodies around the bushes, but as a minimum they will be bored out with oversize butterflies, new bushes inserted and rebuilt on flow bench using new Supertec connecting rods. Will post pics once completed