W460 Engine & Gearbox Issues

Hi 

I have a 1985 LWB G Wagon 2.8 Auto and I have been having problems with the engine & gearbox:

Engine - Low in power and mis firing - I have changed all spark plugs/leads and injectors but still mis-firing. I believe that the petrol pump may be starving the engine of fuel as it is whining quiet loudly when the engine has been running for a while. I think some rust has come away from the fuel tank and is blocking it?

There was also a lot of blue then grey smoke when the engine was warm, I suspect that the head gasket may be the fault?

Blue smoke is a sign of burning engine oil. Grey smoke, if it does not smell sweet/acrid, is probably dirty injectors or lack of fuel. I would;

1.) Check the compression on all cylinders and carry-out a leak-down test. If this passes, then your blue-smoke is probably valve-stem seals that need replacing.

​2.) Change your fuel filter and run some injector cleaner through the system, like BG44K. If you have a rusty or leaky tank, start by addressing that first. The fuel delivery pressure from the pump should be around 3 bar.

​if sweet/acrid grey/white smoke, it may be due to coolant leaking so check cylinder-head gasket and for any oily signs in the coolant or even low coolant level.

​Also, make sure you have a clean air filter an no vacuum leaks after the throttle, which brings us to the gearbox...

Gearbox - Even though it has been looked at by a mechanic the gearbox is still slipping between gears and will not go into 4th gear at all?

Check you have the correct level of fluid (Dexron-II type) in the gearbox. This should be checked with the dipstick at the rear of the engine and with the engine running in P or N. It's surprising that many check the level with engine off, resulting in a low fluid level. It may be good to change the gearbox fluid and pan filter and gasket, whilst at it.

​Then, check that all vacuum lines are intact, without leaks or broken connectors, and that the throttle linkages are good without play. If they have never been changed, then this is the time. The gearbox determines its shifts from throttle position as relayed by the throttle linkages and cables and also by the manifold vacuum.

If you still have issues after this, then it may be time for an overhaul, eevn though this is a very robust and usually trouble-free gearbox.

​Note that the gearbox is designed to start in 2nd gear so you should only notice two up-shifts: one into 3rd and another in to 4th. 1st gear is selected by placing the lever all the way down to '1' or 'B'

If anyone can give me any advice or hints I'd appreciate this. Such as what other makes of Mercedes parts can I put into my G? People say a lot of parts are the same as the Sprinter and the E Class?

in your case, the W123 from the 1970's as far as the gearbox and engine. You should be able to find a haynes manual or equivalent. Brakes and some other parts like door handles are from the Mercedes vans of the 1970/80's

Thanks again