Well some of you may remember a few of my posts when my motor let loose on the highway, warranty was denied, and the whole saga there. I have had the motor apart for a while but noticed a few things last night as I was removing the cams and everything else from the head while preparing it to be sent out. It appears the balancer shaft, as well as both of the cam shafts are covered with heat scoring marks that I did not expect to be there. As far as I/we had previously assumed the motor blew from a spun bearing on #1 rod and the rest let loose from there after the rod snapped. Logic would tell me that the total of 2 seconds of turning over after the first oil was lost from the motor would not be sufficient to heat up these components enough to score them like they are. My question to those who have more experience with blown 4G63 motors is, do these markings show that a lack of oil pressure was the cause of the blown motor? Or is this common with an engine only spinning to a 2 second stop after oil pressure is lost? The oil was lost through the pan where #1 rod poked 4-5 holes so I would think there was even pressure in the system all the way until the engine came to a halt since the oil was not fully drained in those 2 seconds.

Balancer shaft - scoring is very easy to notice


Here is a close up of the cam. Look between lobes and you can see the heat scoring coming from each lobe. These marks are around every point that touches a surface that is supposed to be lubed.


A different shot of the cams where you can see more of the scoring. Look next to every single lobe.


One more shot of the cams


Discuss.

 

Wow, looks like you lost oil pressure.

 

i have see a couple of evo 4g63's with bad water pumps and oil pumps, with only 5-10,000miles on them, its possible the oil pump gave and that why your motor blew, hence this is why i just orderd an oil presure gauge.....

 

Thats what I have been thinking. If I can show a loss of oil pressure caused the failure (i.e. nothing that could be caused by modifications) to NMCA, I will have a great case for wrongful warranty denial.

 

damn bro that sux man

 

well the cams don't bother me. Every set of stock evo cams I've pulled out(10+) has had those heat marks in them. I think it has to do with the fact that they are hollow and more succeptible(sp?) to heat.


So long as the carriers in the head are not scored and look ok I'd not worry. The balancer shaft is unusual though. I woudlnt' expect it to have gotten hot enough to blue it like that.
From what I can see in the picture the smooth bearing seal surface of the shaft looks ok. Can you take a better picture of the balancer shaft?

 

I'll see if I can get a better picture of the shaft tonight when I get home. I just noticed a set of OEM cams in a for sale thread on here that looked like they had the same marks as I noticed on mine.

Sidenote: I thought only the MR came with hollow cams? Yes my cams are hollow, and no it is not from a MR. I must be lacking on my info.

 

The cams look normal like every used set of DSM cams I have seen... nothing to do with being hollow. I never looked at a removed ballance shaft, but it is probably normal as well. A loss of oil pressure would destroy the bearing first, and then the surface that the bearing protects.... not part of the ballance shaft other than the metal to metal contact area.

Keith

 

Craftsman tools kick ***.

 

Eh, they're not bad. I've broken more craftsman sockets and drivers than I have with Snap-on's, but the Snap-on truck isn't as convinient to get to as sears is.

 

not really. They are alright for home use but I dont use them at my work. Snap-on is where its at.

 

It goes both ways actually. I have broken some snap on tools on certain jobs where craftsman tools do it fairly easily and I have broken some craftsman ones when snap on does it easily too. So they are pretty much equal in quality. The only thing you pay for is the truck service for snap on.

I like snap on, craftsman, and matco alot. However, for the price and convenience at sears craftsman is where its at. I mean 1 socket for snap on is like 10-12bucks where as craftsman is like 1-2bucks. And the quality is about the same depending on the tool and what you use it for.

 

From my recollection one of the rod bolt studs has actually loosened up and backed off the stud

This would have caused improper rod end clearance and as a result the oil pressure would have dropped which would have started to eat at the parts on the end of the oil flow chain

Just my two cents

 

Thanks Al.

That was basically my question, as it seems oil pressure was first lost to the #1 rod would pressure still be retained in the head or would the oil path block to that rod bearing cause lower pressure throught the rest of the system up top as well.

 

the cams are heat treated on every lobe for durability. that is normal. i would agree with Al on the rod bolt coming loose and tearing up the bottom end parts. the balance shaft was just hit by debris as it was spinning around at 3200rpm or more. that doesnt suprise me that the warranty isnt covered....FN Mitsubishis....good luck with the rebuild.