So I Pulled My Rb25 Neo Down Over The Weekend...

[JonnoHR31]

Ok, small update. I spoke to my friend who is an engine builder about the lifters. He can't be sure until he has a look over the head, but he suggested either poor maintenance (lack of oil changes), abuse to the engine (starting engine and not allowing it to warm up) or possibly overheating of the engine could have caused the exhaust lifters too look as they are.

Today i decided to pull the bottom end down. I removed all the pistons and the crank. And needless to say, all the bearings are worn and will have to be replaced at the minimum. It doesn't look like they have starved of oil.

My conclusion is its had a very poor service life. Possibly had its first service far too late and may have only had one other service. I know it has been service once here in Australia, as it had a bursons oil filter on it. I would say its also been started, thrown in gear and driven. As thats what most people do;, start > throw in gear > throttle > BAM, heaps of engine wear. Given that most engine wear is caused on start up/warm up. But unfortunately the average person doesn't care/know. i think this is where this engine has received all its damage from.

I'm very very pissed off and frustrated to say the least. This was meant to be an engine to get my car running again until i've finished building my RB26. This is another really annoying set back.

I'm not sure where to go from here. Do i replace all the bearings and rings and set it back to Nissan tolerances. Or for a little bit more money i could put some CP forgies in it, then you might as well put arp bolts in the rods, but for a bit more you could just buy forged rods anyway. Now the crank is out i should get a crank collar fitted and have the crank grub screwed. It just snow balls out of control. Where the hell do i draw the line, a line that i'll be happy with knowing the engine is going to run happily for a decent amount of time to come.

Unfortunately today has got me really questioning myself why the hell i'm into cars, wasting so much money and time and every time i eventually get the damn thing going again, it just breaks something else. Really frustrated and over it! end rant.

if its just a temporary motor throw some new rings and bearings at it and drop it back in. provided you can do it yourself it shouldnt set you back any more than $500 for everything. if you cant do the bottom end find someone local on here who can and offer lots of beer.

[DVS JEZ]

Agreed, hone the bores, new rings and bearings but check bearing clearances before final assembly incase the crank needs work

[Simon-S14]

i think incorrect or too thick an oil can also cause the wear you have seen. esp on cold starts where the oil is too thick to flow between the bucket and head properly.

[kitto]

i think incorrect or too thick an oil can also cause the wear you have seen. esp on cold starts where the oil is too thick to flow between the bucket and head properly.

Simon, Matt Millard also suggested this as another point of wear.

Nissan specify 7.5W30 factory which is pretty thin.

I can change rings/hone bores, change bearings myself.

But trying to work out bearing clearances to nissan specs looks tricky.

[Simon-S14]

Nah it's pretty easy mate theres one page in. the r33 manual that has mains and big end specs. It's 0.025 - 0.050 mm range with a max tolerance of 0.090mm

[Simon-S14]

Btw get the same rings that I'm using. Nisssn ones are quite expensive. JE pro seals suit the neo pistons and are cheap ish