I changed the belt in the 300D today while evacuating the AC system. Did it without taking the fan off, just to see if it can be done.

It can, but I'm black slime up to the elbows -- leaking return line, wondered why I was still smelling diesel fuel after fixing the suction lines to the pump.

Belt comes off OK after releasing the tensioner, but getting it back on is a pain. VERY limited room, worse if you have big hands or arms (it's only my middle section that's big...). Best way to get the belt back on is to pull it up between the alternator pulley and crank pulley, ribs up, then crawl under and fish the other side of the belt around the crank pulley from underneath. There is simply no way to reach the crank pulley from above with the fan on. Had to drag the belt tight on the alternator side to get it over the PS pump, but once it's over the tensioner and the crank, easy. Just dirty. I suppose I need to steam clean that puppy.

It's faster to take the fan off, and easier.

I changed the o-rings at the compressor manifold to pipe connection -- high pressure side was swollen and soft, so hope that was most of the leak. Held vac well, let my good pump run for an hour or more, no 'chatter' from the oil bath so I know nothing was coming out even though my guage set only read 28" -- it's been dropped a couple times.

Blows icy air on R134a now, and I got my leak detector from eBay (GOW MAC 21-150 thermal conductivity meter type) WHILE I was working. If i'd put the job off til this evening, I'd have been more sure of the repair.

I'd suggest snatching one of those GOW MAC leak detectors if you are interested in doing your own AC work -- they can find something like 10-5 cc/min (that is, 0.1 micoliters per minute) of halogenated vapor, and one tenth of that as helium or argon. Don't know if mine works, will test it tonight, but there were three of them last time I looked on eBay, and one was only $30! They run $3500 new.

They work by drawing a stream of gas through a probe and measuring the heat loss (by resistance change) of a fine platinum wire in comparison with another in room air, very very sensitive and explosion proof. Will see anything, including nitrogen, with a different thermal conductivity than air, or whatever gas you hook up to the refrence side.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!