B-series engine breather

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Joined
Oct 31, 2021
Threads
10
Messages
34
Location
bergamo italia
Hi everyone. Can anyone tell me why my engine—which was completely rebuilt 16,000 km ago—is leaving an oil spot on the floor right under the breather hose? Does anyone else have this problem? tank you
 
Get a oil dye kit with a UV light. Treat the oil go for a drive. Use the light to see where the oil is leaking from.

How many miles on the rebuild? Maybe the rings haven't seated - so how much blow by do you have?

+1 for re-torquing the bolts

Who did the work? I see a lot of rebuilt engines that were poorly done

Free download manuals
 
I've covered 15,000 km; it’s not exactly leaking oil—it’s hot oil vapor that drips from the breather hose when it cools down. Maybe the compression is a bit high—32/33 per cylinder. Could that be it?
 
Take a small can, put a few stainless steel pot scrubbers inside and attach the can to the breather hose. Empty every once in a while, rinse off the stainless wool with brake or carb cleaner - put it back on.
 
Thanks, but I wanted to figure out if it's a problem with excessive crankcase pressure. I think I'll take it in for a leak-down test.

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Maybe when they rebuilt it they left out some sort of baffle plate. Test the blow by removing the oil cap and put your hand over the hole with the engine idling - you should feel pulses - they should not be excessive. Look in the manual to see what/where things related to the breather.

there is a diesel forum around here some - look there.

Leak down is a good test for valves and rings providing more information than a regular compression test.
 
bj40 3000 diesel del dicembre 1980
Do they all have that stain underneath? I wonder why it didn't do that before the engine rebuild. I also think it might be due to the engine block being decked by two-tenths, which raised the compression too much.
 
Yeah, every B or 3b diesel truck I've ever been under ( lots ) has an oily front driveshaft because the tube is directly above. Not much in the way of baffling before the pipe either. Just kindof a messy design.

I was going to experiment with adding a second crankcase vent to my valve cover to see if it helped with the oily floor. Haven't got around to it yet.

Mine has a turbo, so there's a little extra wind inside the lump.
 
I doubt that little amount of decking made a huge difference in compression. But ring seating can be an issue with the wrong break in oil and technique.
 
The 13b fed the breather back into the inlet ducting but that makes a mess of your manifold and the rubber duct - I just fed my breather pipe into my chassis rail, bit of British rustproofing. Wouldn't be too concerned - you'll be in much more trouble if you break a glow plug doing a leakdown. If its not using oil its fine.
 
Thanks for your replies. I would also like an opinion regarding compression. The manual specifies a minimum compression of 30 kg/cm², and elsewhere mentions a minimum compression of 20 kg/cm².
In your opinion, what could the maximum compression reach?
 
 
SOP, most of the time it just hits the driveshaft, bend the tube a bit so it does, prob solved
 
bj40 3000 diesel del dicembre 1980
Do they all have that stain underneath? I wonder why it didn't do that before the engine rebuild. I also think it might be due to the engine block being decked by two-tenths, which raised the compression too much.
Hi, I also suspect it’s a compression issue, which is why I was thinking of performing a cylinder leak-down test. I’m not sure if other BJ40s have the same problem; I’ve noticed that no one on the forum has replied mentioning a similar issue.
 
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