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Driving to work this morning got me thinking. I don't believe the MFI belt on my 73 911e has ever been replaced.
The engine and MFI were rebuilt 8 years ago but I don't believe the belt was ever replaced. Nothing lasts for ever and wonder if it could be missing some teeth or is about to fail.
Can the MFI belt be replaced with the engine in the car? Are they still available? Any tricks to the trade?
Thanks,
Chris
73 911 E
Chris,
Yes, the belts do wear but they tend to stretch rather than loose teeth...
They're surprisingly durable
Yes, they can be replaced in the car....
Yes, there are some tricks to the R&R
What you should be looking for is a worn out MFI gear, they're made of a very light mag alloy of some type that just gets ground shiny from the not very tight tension of the belt.....
Hope this helps
Cheers,
Chris--
Yes, they can be replaced by doing a partial drop. The factory procedure for this begins with removing the port side heat exchanger. Anytime you read that, it's a good idea to consider doing a full drop to take care of all the other things you can do-- personally I never changed the race car's belt because the prospect of snapping off exhaust studs when removing the HE was too much to handle.
Anyway, if you did a partial drop to get some clearance ahead of the engine below the crossmember, got the engine tin off, you would then need to remove the stacks (the crossbar is in the way, as is the port-side stack) and then remove the MFI lines- (CAREFUL-- fuel will spray out and cause a fireball if there are any ignition sources, so extinguish your Monte Cristo No. 2 before performing this procedure) then loosen the pump so you can get the belt on. Probably at that point you would remove the pump to check out the pulley, it's easy enough to get back on. Repro pulleys are available hard-anodized, not cheap at about $150 or higher, but if your teeth are worn, critical to replace. At that point you could change seals on the top of the engine around the crankcase breather, change the cohline oil supply line with the banjo to the oil pressure gauge, etc. Easy to get sucked in to concours projects "while you are in there."
All in all it's a frustrating full weekend of work if you are experienced. I've done lots of work on my MFI pump and it's not intellectually challenging, just time consuming.
Good luck!
not that complex. Just did is a couple of weekends ago in a couple of hours. First you need to remove the rear divers side wheel. Jack up the car and get in on jack stands using the torsion bar ends. Get the wheel off. Then you need to position the engine to get the belt on. Read about how to align the engine and the MFI timing mark. Get some long bolts for the engine mount. Place a lift jack under the engine to support it. Remove the engine mount bolts and replace with the longer bolts (about 4-5 inches) Use some good washers to help with the support. Slowly lower the engine down the the bolts until the stop point. you are going to have to remove a couple of things to make it easy. I took off the trumpets and air tray on the driver's side from the MFI stack. You also need to losten up the sheet metal on the rear of the engine that covers the MFI belt (About 4-5 screws). I was able to pop the MFI belt off the pump and then off the cam and remove it. You can slip one back on the same way, cam then pump. there are three allen screws on the mfi sprocket that you can lossen up and reposition the the mfi pump mark. That is about it, and I am sure there is a better description out there then this abbreviate one. But you will need to spend about a 1/2 day or so if it is your first time. I can do it in a couple of hours now......
Oh and get a magnet to fish out all the stuff you drop :)
Hi John,Quote:
Originally Posted by 304065
Can you provide a source for repro MFI Pulleys? Are they good quality comparable to OEM?
Thanks,
I have a set ( upper on pump and lower on cam ) that I'm not going to use and are hard anodized if anyone needs them. Isn't the bottom one with the extra lip?