I guess this is where I need to post this.
I hope some of you knowledgeable members can help me out. I'm looking at a 4D31 Mitsubishi engine that came out of a 1990 Fuso to swap into my '85 Toyota 4x4. I understand that it spits oil out of the valve cover breather under heavy sustained loads. Does anybody know what the cause and remedy would be for this? Also, does anyone have any specs on this engine such as weight, horse power, etc.?
I thank you for your knowledge.

 

Just because you are putting a Mitsubishi engine into a Toyota doesn't mean a lot of people here are going to know much about the Mitsu engine. However, a quick Google search shows me the Mitsu 4D31 engine is a diesel, which has a much higher compression ratio than a gasoline engine. I would suspect that the piston rings aren't sealing well under heavier loads, either due to worn rings or a poor design. That means some compression is leaking past the rings into the crankcase (blow-by), pressurizing the crankcase & causing the oil to get blown out the valve cover breather. If it's due to a poor design there will be no stopping it from happening. If the rings are worn the engine needs a rebuild. It's also possible that the turbo is leaking pressure into the oil system, so you would need to rebuild the turbo with new seals or get a re-manufactured turbo.

The same quick Google search turned up the following specs on the engine:

Model 4D31 3298 cc (3.3 LIter), bore x stroke is 100 x 105 mm, overhead valve turbo direct injection, peak power is 100–130 PS (Horsepower) or 74–96 kW @ 3500 RPM, Torque 30 kg-m or 217 foot/pounds @ 2000 RPM. Produced 1985 to 1995.

Good luck with it.

 

Thank you for your reply, 13swords. I don't know why I have such a problem finding the basic stuff, thanks for you taking the time to look for me. Someone else mentioned that there could be an exhaust valve not working properly that could cause that spitting too. Would you concur? One concern I've had is if the front axle could handle the weight alright, and another thing would be the transmission holding up to the torque if I can find a way to mount it.
Any further thoughts or directions would be appreciated.

 

You are welcome. Yes. an exhaust valve that is sticking closed on the exhaust stroke could cause that issue. Since the valve stays closed when it is supposed to be open, the exhaust gases cannot go into the exhaust system, so they try to go somewhere else. Going past the piston rings seems a reasonable assumption. If any of the valves on that engine are sticking open or closed, again, it needs a rebuild to get it to work properly. Good sealing of piston rings & valves are even more crucial in a diesel engine, due to the much higher compression ratios. The diesel is probably around 20 to 1 ratio, where the gasoline/petrol engine (Toyota 22RE) is 9.3 to 1 ratio.

I understand your concern about the weight & the front axle. The best estimate I can find (I could not find exact numbers for this) is that the diesel is about 2 times heavier than the gasoline engine. The 22RE is about 350 pounds and the diesel is around 750 pounds. This makes sense to me. The diesel engine block has to have more metal in it (stronger main bearing journals, thicker cylinder walls, etc.) because of the higher pressures involved. I personally wouldn't be worried about the axle taking it, I'd be more concerned with the stock Torsion Bars and whether they could handle it or not. I do not have nor can I find specific information or specs on the stock bars. I did however find this:

https://swayaway.com/product-categor...ars/tb-toyota/

Sway a Way has been making suspension parts for a very long time & the quality looks good. The description says they have higher spring rates than stock bars (the stock bars are no longer available from Toyota) so that might help with the extra engine weight, especially if you also get some quality Urethane bushings to go with them. There seems to be 2 different lengths of bars. 35.125" or 892.175 mm, or 41.875" or 1063.625 mm. Both have 25mm diameter. I guess you'd haveto measure what is in your truck to get the right length. Sorry I can't be more specific on this, but my knowledge on the 4x4 models is limited.

If you mean will the stock Toyota transmission hold up to the diesel, my opinion is that it should, IF you don't push it hard. Toyota transmissions (especially manuals) are very well engineered & built. They always over-built their components so they would be reliable. The 1985 4x4 Pickup had an option for a turbocharged fuel injected engine that made 101 kW 137 PS 135 hp @ 4800 RPM and 234 N-m 173 lb-ft @ 2800 RPM. Those numbers are pretty close to the numbers on your Mitsu engine, so I assume the trans would handle it.

Mounting the Mitsu engine isn't that complicated I wouldn't think, IF you have some good fabricating skills. It might take some designing & welding, but custom motor mounts would do it. The biggest obstacle you have to clear is how to mount the engine to the trans & have it all work right (correct alignment, starter compatibility, etc.) You would either need an adapter plate (which I could not find any for this combo online) or have the trans bellhousing machined for new bolt locations, etc. I personally wouldn't want to get into that, as I do not have the knowledge to do it. It could be a very large & involved project.

That's about all I can give you. I have never done an engine swap like this before so my knowledge is limited, but I am a decent researcher.

 

That, my friend, you most definitely are. I'm going to copy what you have posted to my word file so that I have it later. Very good information about the sway bars, I will be looking into that, no doubt. This sets my mind at ease about the weight issue. I think this would make a very powerful little truck to play around with as well as a good woods working truck once I get it all put together. Now I just need to see about getting it shipped here.
Thanks again.
P.S. If you happen to come across any more info., please don't hesitate to share.

 

Thank you, I do what I can.