Loss Of Power and Lots Of White/Grey Smoke On Mitsubishi 3 Cylinder Diesel

bigdeano · Jul 13, 2013

Let us know what went wrong please when you get it apart. Hope it's not too expensive.

JLinknc · Jul 14, 2013

I pulled the head and oil pan off and found the problem. It appears the rod bolts were working lose which caused lots of play in that one cylinder. Don't know if maybe that extra play caused the timing with the injector to be off which in returned caused the diesel smelling smoke. Cylinder wall looks good with no scoring, crank looks good with no scoring, no signs that the valves or springs are burnt/broke/bent, head gasket looked good with no signs that it blew out. At this point since the other two cylinders had in excess of 525 psi of compression, I'm thinking about honing the one cylinder, installing a new set of rings and rod bearings on that cylinder and installing a new head gasket and putting her back together. The motor is on an older 4WD Toro Groundsmaster Mower with 4000 hours and is not worth sinking a ton of money into since I don't have a clue as to how much longer the hydraulic drive unit will hold up. I had plans of retiring it at the end of the mowing season and using it as a backup mower to the new one I am planning to buy. I have the torque specs for the rod bolts and head bolts but do not have a torque pattern for the head. I'm hoping whoever I buy the parts from can provide me with the torque pattern since I have been unable to find one online.

bigdeano · Jul 14, 2013

Hope that fixes it for you. I don't see how that caused the low compression though. Be sure to inspect the piston carefully in case it's cracked.

Don87 · Jul 14, 2013

bigdeano said:
Hope that fixes it for you. I don't see how that caused the low compression though. Be sure to inspect the piston carefully in case it's cracked.

+1...

muddstopper · Jul 14, 2013

JLinknc said:
I pulled the head and oil pan off and found the problem. It appears the rod bolts were working lose which caused lots of play in that one cylinder.

I'm thinking about honing the one cylinder, installing a new set of rings and rod bearings on that cylinder and installing a new head gasket and putting her back together.

I would think first before I put new bearing in a rod that is obviously stretched. If the bolts worked loose, there is a reason. Simply putting new bearing in isnt going to fix the problem. Engine running and rod bolts working loose most likely would mean and out of round rod cap and sever scoring on the crankshaft. New bearing wont fix this problem. Since you are going to have to tear it down anyways, at least while you have the rod and piston out, Install new rod bolts and torque them down and then measure the inside dia and see if it matches factory specs. Also mic the crankshaft and see if the crank is worn more than tolerances. It is possible that you might get away with just installing new bearings and buttoning everything back up, but you could also waste a lot of money and not solve anything and possibly put yourself in a position where it could cost you more money than you really needed to spend.

sox3 · Jul 15, 2013

bigdeano said:
Hope that fixes it for you. I don't see how that caused the low compression though. Be sure to inspect the piston carefully in case it's cracked.

I have to agree here, lose rod bolts wont cause a low compression like that. Need to look a litter further at Head,
Valves and pull the piston out to inspect.

jrsavoie · Oct 27, 2014

sO WHAT WAS THE VERDICT?

I am having a similar problem with my Groundsmaster now. Is there anybody close that would get it going good for me?

It had a blown head gasket. Head has been shaved 7 to 9 thousandths. I put it back together and it has a lot of blowby. The number 2 cylinder is weak on mine. 140 lbs. With a little oil the pressure comes right up.

It smokes and runs rough when started but smoothes out and runs good - seems like full power after warmed up.

Pager450N · Dec 23, 2014

I have hadsimilar issues with mine, (just joined today) and I am currently rebuilding mine. I also had issues like jrsavoie and #2 going south. It had 140 psi, then with some oil it went to 190psi. I had a tough time starting the engine, alomst 10 minutes of on and off cranking. So, I got an itch and tore into it. Heres what I found, #2 had significant wear on the wall, (enought to have to go to .025 oversized) and had a lot of blowby.

Please be mindful of these little engins. If your having a tough time with starting, idle or power, do a compression check and if one is low, pull the head. Im telling you that if you prolong it, you could be in my shoes. Im looking at a $600 bill for just 3 oversized pistons and rings. Thats not including the gasket kit, new connecting rod bearings and mains.

Good luck!

Scott65 · Dec 23, 2014

When you guys are checking compression, where are you doing it from? I'm a diesel mechanic but I'm unfamiliar with these engines. Are you using a glow plug hole, or removing injector? If the injector is still in, you can't rely on your readings. The compression could be back feeding into a faulty fuel system. And if so, that would explain some of the mechanical symptoms. Normally a grey smoke and knocking engine is too much fuel in the cylinder, which will wash out cylinders, bend rods, break pistons, and can transfer this damage down to the crank. Just a thought

jrsavoie · Apr 27, 2020

My issue was the #2 nipple in the injection pump was not tight. They are supposed to be 20 or 25 ft lbs. My was loose. I was first told by a diesel mechanic that it was set in position by the lock ring. Not so. I was told later that it was supposed to be torqued. Tightened it up and the machine ran great. Now I have water in the oil. With the tester on the radiator set at 14 psi, it lost 3 lbs in 3 hours. Does anybody know a likely spot on these engines?