I need a little diagnostic help...I rebuilt my 4BT earlier this year and I've been struggling with what I feel is a over fueling problem since the first time I started it. The engine ran fine prior to the rebuild (maybe I should have just left it alone ), but I wanted to freshen it up and gain the experience of the rebuild.

The problem is excessive white smoke, raw fuel or oil discharge at the exhaust, and at the slightest bump of the throttle it wants to runaway.

The IP timing has been triple checked in the gear case and with the existing marks. I have also tried adjusting the timing from 6* to 17* advance with no change.

Compression is 450+- across all cylinders after just 3 strokes on a cold engine.

Coolant and oil systems are clean with no evidence of head gasket failure.

I've ran the engine to 180* and bled all air from the fuel and injector system.

When I did the rebuild, I put in Arias coated pistons for added EGT durability with piston / cylinder clearance of .009 per Arias recommendations.

The IP has been double checked by Diamond Diesel along with new stock injectors.

The inside of the intake plenum is clean with no evidence of oil or turbo failure. The H1C is rebuilt and produces boost pressures of about 24lbs.

Here is what I suspect...After the engine is run for a about 10 to 20 minutes I check the oil and find the engine has used about a liter of oil. I think for some reason I'm pulling oil from the crankcase into the cylinder and the engine attempts burn the oil. Is this possible?

If I don't find the answer, I'm going to have to take the engine back down. I would like to understand what I'm looking for prior to the disassembly.

Thanks in advance for any support.

 

Oh yeah, they will run on their own oil.

Which injection pump does your 4BT have?

 

Bosch VE with KSB advance.

 

That smoke is probably engine oil burning, since your oil consumption is high and you didn't mention any leakage-- which would be VERY obvious at that rate of consumption!

You need to break it in hard if you haven't already done so--but I suspect that your ring seal is perfectly fine (good compression readings and high consumption).

There are two things I think you should look at

First are valve seals. I suspect that your valve seals might be leaking a LOT of oil into the engine, most likely on the exhaust side (bad seals on intake side will not be as clean as you mentioned the intake is).

Second is the seal of the injector to the head. That copper sealing washer might be missing, doubled up, or just damaged. If the injectors aren't properly seated in the head, oil can run into the chamber from the top end.

I'm pretty confident that one of these two things is your problem.

JMO

 

First are valve seals. I suspect that your valve seals might be leaking a LOT of oil into the engine, most likely on the exhaust side (bad seals on intake side will not be as clean as you mentioned the intake is).


Good point I'll put that on my list when I break it down. The injector washers are new and the injectors are torqued to 44nm.

Thanks

 

Take the exhaust manifold off and plug the tubo oil feed line. Run it with no manifold and see which cylinder the smoke is coming from. At least then you will know which cylinder is causing this if not all of them.

 

Wow, burning a liter of oil in 10 to 20 minutes! You are close to an uncontrolled runaway.

The turbo seal seems like the perfect place for that kind of a situation, but you say the intake is oil free. Hmm.

It's hard to imagine that much oil passing the valve stems because there is next to no vacuum there and, under boost, none.

Is there some way the VE pump can be getting oil from the crankcase past the seal on it's shaft?

Of course your crankcase breather is open, right?

 

Not on a 8 valve engine.

No, if the shaft seal was bad he'd be making lots of oil.

A clogged breather is a good idea though.

Didja forget the oil rings on the pistons maybe?

 

Nice try ...but no I gapped all the rings; as a set, for each cylinder.

Thanks

 

Here are some pics of the 4bt.

 

Look great, it's a shame it's giving you fits.

This much oil consumption with a clean intake tract is puzzling, usually they will be pulling it in through a bad turbo seal.

Is the breather free of restrictions? In the final image I can see something clamped to the tube.

 

Thats a blue hose about 14" long to get the vent away from the engine. I put air into the oil filler cap and it was exiting out the hose to test the vent.

 

Sweet little engine! God what I'd give for one of those in a little dakota 4x4 as a second more efficient truck for small jobs.

 

Seems to me that if the intake is clean and the valve seals aren't totally MIA (and I've never seen valve seals move that amount of oil) then the only place to suck oil is through the head gasket. Is it possible that the gasket you have is for a different application? Any possibility that the oil rings got in there upside down?