Today I did a jiggle test as described in the FAQs on my 91 740 non turbo to see if I had sufficient vacuum. Well the oil cap jiggled out of position and across the valve cover. The FAQs went on to say that this test is only applicable with the earlier metal caps and not the later plastic oil caps. The thing is I am not sure what I have as there isn't anything for me to compare it to . Is it reasonable to say I have the plastic cap on my 91?

Its all done now , I got to know the car a bit more by removing the manifold and seeing all the sensors on the side of the block. The breather box can be removed without taking off the manifold but there is that hose that takes coolant to the heater valve that sits right on top of it and the space fo me was so cramped I thought it best to remove the intake manifold. This is also a perfect time to renew that hose. It is also a great idea to remove the negative cable of the battery .

My 90 has a metal cap - the top of it is chrome and it's quite weighty. It should be apparent if it is metal... not sure if it's not shiny chrome.

As for the breather box replacement - I had an oem (I think) box, cleaned it (with brake cleaner) a few years back, and had it fail on a seam (horizontal, not vertical).

I did the job twice and I never removed the intake manifold, and the only thing that was a pain was that my car has an EGR (CA only?) setup.

The EGR runs exhaust gas through it... read stuck bolts... and shares mounting bolts with the breather box. The only difficult part about the job was removing the EGR and a wiring bundle that got in the way on re-install.


Good Luck,
Will

PS I think you could feel for vacuum just by putting your hand on the oil fill hole and covering it completely.
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1990 740 Turbo, on its way to stock specs, maybe beyond

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You almost certainly have the plastic cap. Does it look like this?
http://www.fcpgroton.com/images/products/large/8692888.JPG

that's the plastic one. I think the B230 only came with the plastic caps, it was the B21/B23 that had various incarnations of metal caps.

john

85 740. All metal
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Post Back. That's whats makes this forum work.

One day soon I will tackle the breather box but the fact that the tube to the oil pan can be dislodged and fall into the oil pan is upsetting. Has anyone replaced or cleaned out the breather box?

Yes, I've done it on the 945 and the 245 with no trouble. The 945 was done early on, one of the first reasonably involved bits of maintenance I tackled on the car. Awkward, but not hard. Took me 2 hours, being careful and not removing the intake b/c I was nervous about getting in too deep.

Make sure you have a new o-ring for in between the box and the block (and make sure the old one is accounted for and removed--it was stuck fast to the block on one of my cars).

This is much less tedious if you take the intake manifold off, so it is not a bad idea to have a new intake gasket on hand. Heck, be real thorough and plan on cleaning the throttle and replacing the throttle gasket while you're there. Just have a magnet on hand to retrieve the intake nut you will drop into a dark crevice while trying to thread them back onto the studs during reinstallation.

It is true you don't want to mess with the front drain tube under the box, but I can't imagine how you'd disturb it accidentally. From my experiences with this, it would take some intentional and vigorous poking and prodding at the tube to create a problem.

There have been numerous reports here that the aftermarket box from FCP is crap. The 945 has that box, no problems after 1 year and 12k. The 245 got an OE box from Tasca, FWIW.

John

John ,
You read my mind in that my method will be similar to what you described except that I overlooked the TB cleaning , gasket and magnet..good suggestions. I was looking at Eeuroparts last night and with free shipping they had all the parts. The box from fcp looks like the updated style but thatks for the heads upregarding it. I am going to do the "blow " test today to see if I am dealing with a lot of resistance in the system . BTW do you think the down tube into the block is worth changing ? The reason I am asking is that I changed the flame trap and the tube to the box last year and I could not believe the amount of crud that lined the inner part of that tube .

I wouldn't mess with the tube. I don't remember there being much crud in either one of mine, and the box and flame trap on the 245 were unbelievably vile. The s-tube between the flame trap and the box was about 3/4 clogged, and the box felt like it was filled with lead fishing weights. It turned out I had a leaking headgasket that was letting combustion chamber stuff into the oil galleries--no wonder there was carbon everywhere.

My understanding of the box's purpose is that it's meant to give cruddy oily vapors a place to separate into their three component parts: oil that runs down the tube to the sump, air that gets sucked into the intake, and carbony crud that builds up in the box. The crud should stay in the box, not go down the tube.

John

Thanks John, I am not going to mess with that tube , however I will do my best with the breather box.

Hello Paul,

I don't frequent the 700 board, but tonight I felt like lurking around.

I've had bad luck with aftermarket breather boxes. I'm assuming the 240's and 740's are identical.

The original breather boxes ave two vertical seams that are heat welded. You can tell because there's a ragged melted edge at the weld location. The aftermarkets, although they look the same appear to be "welded" with pvc solvent.

I installed two on my 93 240's and both of them leaked. I took them in the house and filled them with water to be sure, so I know.

I think Randy Starkie (I'm not sure if he deserves the credit) said just take out the old one and clean it out with gasoline and reinstall with a new o-ring.
Short of picking one up at the JY, that's what I will do in the future. I replaced both of them with Volvo units from Tasca. You could probably pick up the discussion if you search the archives for breather box.

Good luck with whatever you decide but I wouldn't use the aftermarket boxes.

Marty Wolfson

I think Randy Starkie (I'm not sure if he deserves the credit) said just take out the old one and clean it out with gasoline and reinstall with a new o-ring.

I'll take the credit if the procedure works but not the blame if it does not (grin).

The original boxes are tough and it is my understanding the aftermarket replacement are just plain junk.

I remove the boxes and use a 3/8" drill bit to ream out the opening the hose fits to. I then take a small hammer and tap all over the outside of the box. This knocks loose a lot of the build up inside. I shake that out and repeat making sure to make flat impact blows to the surface and avoiding hitting with the edge of the hammer. After I have removed all I can that way I turn it upside down after plugging the top opening. Then I pour it full of gasoline and let it soak- the longer the better; overnight works for me. Dispose of the gasoline in an appropriate manner, install a new Oring, and bolt it down.

Randy

Advice taken gentlemen , I will reuse the old one after cleaning it.

Lots of folks here have done it with no issues.
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Post Back. That's whats makes this forum work.

Thanks John..yep Ive got the plastic one and thanks for the link..I feel a little better now even though as part of my mainetenace I will address the breather box in the near future