Finding TDC on MF 255

[bailes]

I need to pull the injector pump on my MF 255 for rebuild (diesel leaking into oil crankcase). Is there a way to find TDC on the Perkins 3.9L besides opening the valve cover? I see no timing marks on the timing chain cover or the harmonic balancer. Thanks.

 

[Jim.ME]

Welcome to the forums.

Before you get into pulling the injection pump, have you checked out the lift/transfer pump? Those can be a more likely a source putting fuel in the oil than the injection pump and will be a less expensive repair to replace it than have the injection pump overhauled.

Massey Ferguson publication number 1448768M1 is the service manual for the 255/265/275 tractors and has the injection pump removal and installation information for the three Perkins diesels used by those tractors. The timing marks are on the flywheel I believe. They will line up every rotation so checking the valves on #1 cylinder is the way to confirm you have it on #1 compression. I believe that injection pump uses a pin in a slot at the drive hub so it should be easy to reinstall.

 

[bailes]

I changed the lift pump hoping that would solve the problem. No joy. I saw the mark on the inspection hole for the flywheel but wasn't sure that was a way to find TDC. Thanks.

 

[Harry in Ky]

If it's a Perkins 236 you don't need timing marks. Just look at the pump mounting flange where it meets the timing cover. There will be a series of marks right there, and (usually) just one on the pump flange. I take a sharp scribe and accentuate where they meet. Then just remove the pump.

Drain the coolant , remove the lower radiator hose and the tin cover from in front of the pump drive gear. Inside are three bolts (5/16 SAE) that hold the gear to the pump drive hub. Remove them and lift the pump off. There is a hole in the gear that matches a roll pin in the hub so the hub and gear cannot be installed incorrectly. The gear can't get out of time but I wouldn't rotate the engine while the pump is off.

When the pump goes back on, install the three bolts in the hub, and match up the marks on the outside. Timing is done. The rest is just nuts, bolts, and fuel lines. No manual needed.

 

[MF#1]

I did one on a 203D 255 several years ago, didn't use any timing marks. Took it off as Harry said, had it rebuilt, and put it back on only aligning the timing mark back to where it was before snugging it up. Ran/runs fine.

 

[Jim.ME]

The marks will be there, but you need to look at the valves to confirm if #1 is on exhaust stroke or compression stroke, if you want to confirm #1 TDC.

The manual tells you about removing and installing the injection pump and the pin in the hub to match the slot in the gear. You don't need TDC if you do that.

 

[MFEngineer]

Be sure to align the pin with the slot before bolting the flange back to the gear. I've had people adamant that there's a problem with their pump after we've rebuilt it, only to find that they've tightened the flange bolts in the wrong position and pushed the roll pin through the gear.