Blow by!!!

Does your Mitsubishi L300 make a strange noise? Need wheel alignment specs?
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WestCoastr
Posts: 19
Joined: Sun Mar 11, 2018 11:18 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: 92 L300
Location: Tofino

Blow by!!!

Post by WestCoastr » Wed Jul 24, 2019 12:57 pm

Hi all,

92 l300 250km on her with a new head replacement completed this spring. For those of you that followed my last post that was miss titled "squeal while on throttle" it was my injectors causing the low performance and smokey running. I fitted the van with used injectors and I'm happy to say that it runs excellent. So, great that I'm surprised it has such a significant blow by issue. This is likely something I should have been aware of before I did the head replacement considering the intake was caked with oil, but I'm a noob so of course its always trial by error. My thought initially was that my leaky turbo was the main culprit (and maybe it is?) The spindle had minimal play last time I checked with just a bit of oil pooling. However, I finally took the oil cap off while investigating why my waste gate keeps popping at 3200 rpms (too much boost?) to find white smoke coming out! I understand blow by in diesels is quite normal at low levels but is actually seeing white smoke a low level? Again, the girl runs great (right now). Could I have damaged the piston rings when doing the head replacement? I was very careful to keep any crud out of the cylinders (i think). She has good coolant temps when driving with a bit of climb towards the half way mark on longer hills and its pretty hot here right now. about 30 degrees Celsius. I don't have a pyrometer so I couldn't tell you what the exhaust gas temps are doing and the previous owner had plated and deleted the egr. There still seems to be some oil leaking from the drivers side of the engine. Despite replacing nearly all the lines over there.

Aside from all that. The vans pretty close to where I want her to be. Needs new transmission mounts, drum brakes, suspension will need some love in time, and of course all the lovely rust. Just looking for some thoughts on this. Is she hooped? ha.

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Growlerbearnz
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Vehicle: Delica P25W
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Post by Growlerbearnz » Thu Jul 25, 2019 3:10 pm

The 4D56 is a notoriously heavy breather, especially if it wasn't serviced properly before you got it (oil changes every 5000km!). With the EGR removed the oil won't do any harm, unless it gets so bad the engine starts to run on its own oil and can't be stopped. That's unlikely unless something goes seriously wrong in the engine.

The only way to tell for sure what's going on is with a compression test. Normal is 440psi, lower limit (worn out engine) is 320psi, with no more than 45psi difference between any two cylinders.

You can reduce the amount of oil making it back into the intake by fitting an oil separator/catch can, but it needs to have large ports and large diameter hoses going to it. If the hoses are too small or too long you can restrict engine breathing, which will pressurise the engine and make all your oil leaks worse.
There's also not much room to fit an oil separator in the engine bay. I fitted a ProVent200 with 1" hoses, but making it fit in the air filter compartment and routing all the hoses was an utter nightmare.

The thing that's popping at 3200rpm will be the pressure relief valve on the intake manifold. (The wastegate is built into the turbo and doesn't make any noise). The relief valve opens at around 12psi, but they can get tired when they get old. I'd fit a cheap boost gauge (even temporarily) to confirm what pressure the valve is blowing at. If you want to turn your boost up you'll need to disable that valve. You can replace it with a male 1" BSPT thread plumbing bung, but if you disable it you'll need a boost gauge so you can watch boost pressures, just in case something goes wrong.
Nothing says "poor workmanship" more than wrinkles in the duct tape.

WestCoastr
Posts: 19
Joined: Sun Mar 11, 2018 11:18 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: 92 L300
Location: Tofino

Blow by!!!

Post by WestCoastr » Thu Jul 25, 2019 9:10 pm

Your an absolute legend Growler. Ill work at doing a compression test in due time here. Is there any chance that when you have time (no rush) you could share some photos of your catch can set up? I saw a video (youtube) where it was mounted near the fuel filter with about 2 1/2 feet of 1 inch hose going to and from the can. Just out of curiosity. Knowing that you have the nearly new crate motor installed. How much blow by do you have? Is it enough that there is actual white smoke puffing out of the oil cap after a quick trip up to operating temps?

I also saw that you will be doing the trans mounts soon. I'm just about to put my order in for those (after my compression test likely) as my tranny is probably sitting 3/4 inch lower than it should. However, I'm fairly certain these bolts arn't going to slide out all that easy. Already got the pen lube on them but im thinking I will be drilling them out. :-(

WestCoastr
Posts: 19
Joined: Sun Mar 11, 2018 11:18 am
Member's Photo Album: http://www.delica.ca/Photos/
Vehicle: 92 L300
Location: Tofino

Blow by!!!

Post by WestCoastr » Sat Jul 27, 2019 2:54 pm

Also curious, where did you run the oil return port on the provent 200?

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