I'm preparing to install a refurbished turbo on a 1994 940. Yes, the brickboard FAQs here are very helpful but I have some questions.

1 -- Regarding replacing the turbo oil supply line -- what exactly is the procedure to get the banjo bolt (19mm?) off the engine block?

The banjo bolt going into the engine block is located right behind the oil cooler sandwich plate / sender unit (OCSPSU). Looks to me that this 19mm banjo bolt is pretty much inaccessible without removal of the said OCSPSU. Is removal of this OCSPSU a big deal -- is it just a matter of removing the 36mm banjo bolt securing it to the block?

Any comments welcome ...

I never remove the banjo bolt in the block when I do a turbo.
I find it much easier to undo the bolt at the turbo end of the oil line.
If you are pulling all the parts in the exhaust side of the engine I'd still disconnect at the turbo, when it is out it is much easier to get to all the parts underneath it.
Toughest part is the oil return line which doesn't like to come out with the turbo.
I pull the O2 sensor which gives me enough room to get a wrench on the 2 bolts holding the oil return line to the turbo.

There is a stiff leg bracing the oil cooler assembly. It is held in place by one of the engine mount blots. I would remove it first. Then remove the 36mm head hollow bolt and push the oil cooler assembly away from the 19mm banjo bolt. You may find it easier to remove the oil filter and disconnect the two coolant hoses and remove the oil cooler assembly completely.

It is a good time to replace the two coolant hoses connecting to the oil cooler. I would definitely have a new o-ring to install between the oil cooler and the block. There is another o-ring between the oil cooler extension and the oil cooler. They eventually leak, so you might want to replace it.
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john

Thanks, John -- I see what you are suggesting. I'll take your advice.
One thing is leading to another with this turbo (220K) replacement. Really quite a challenge and expense. Turbo growling and not performing, I pulled the turbo, sent to Tims Turbos of Falls Church VA and he declared it unworthy of further attention. $675 for a rebuild (reasonable price, looks great). Now it's "while I'm about it, I might as well replace this, that, etc." Worth it if I can get another 220K ...

My 1994 940T has 327,xxx miles. It has the original turbo. I had to replace the head gasket last winter, the transmission about two months ago, and the radiator about three months ago. I also replaced the heater core a few years ago. The rear main seal I did several years ago.

It has been a great car.
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john

That's interesting information on the main big-ticket items to expect to have to deal with. I don't believe my car has been maintained as well as yours, but there is no rust so I'm planning on keeping it running if at all possible (my wife thinks I'm crazy because the paintwork isn't up to much).

During this troublesome turbo teardown -- which I would rate more difficult than would be suggested by the 900 FAQs -- it has crossed my mind to do the head gasket "while I'm about it". The head gasket on my 92 740 non-turbo lasted 220K (and that job wasn't too bad), so I'm expecting HG issues on the 940 before long. Still, cars can be like people, you never know what they are going to do or say next. I'll probably end up getting new nuts for the turbo->manifold connection ($10 each!) and make sure I can get them off again without too much trouble, just in case. I would do the manifold studs (these remain in fair condition), but it's not obvious to me how to get those off. If they were willing to come out they would have budged already, surely ...

Dear rob2volvos,

Hope you're well. I've replaced exhaust manifold gaskets on two 940s (non-turbo). I cleaned the stud ends with a small wire brush, to remove rust. I then repeatedly saturated the stud ends and nuts with PB Blaster, a penetrating oil. As best I recall, I applied PB Blaster daily (or twice daily) for a week.

A penetrating oil can need a lot of time to work its way through micro-channels in the corrosion, and so to weaken the corrosion bond.

After the final PB Blaster soaking and before trying to loosen the nuts, I "tightened" them, i.e., I applied torque as if I were tightening the nuts. I did this gently. I thought even .001" of movement would further weaken any corrosion bond.

I then loosened the nuts, using a ring wrench. With some hesitations - but no broken studs or rounding - the nuts came free.

When I replaced the nuts, I coated the studs with a nickel-based anti-seize rated for 2,500⁰F. I hope this will ease the next exhaust manifold gasket change.

Hope this helps.

Yours faithfully,

Spook