RB26 rebuild problems (oil squirters)

[Amaru]

Just wondering if anyone else has had this problem or could tell me which of the two things happened. Ill give the scenario out first.

Engine was rebuild around 12 months ago, using standard (shot peened and polished) rods, Arias 20 thou overbore forged pistons. We had the sump off the car today (I also have pictures to show it can be done relatively easy without removing the engine, and also cheaper labour than removing the engine - R32 GTR) for various reasons, and there was some metal in the sump. After getting the metal pieces out, it was obvious all the oil squirters in the cylinders have snapped off. They appear pretty flimsy and look like theyve just been clipped by the piston and come off.

The two scenarios I have been given are, Arias stuffed up making them and they're a fraction too big, or the engine builder got the clearances wrong. When everything was installed, they turned the engine by hand, and everything cleared, my mechanic is telling me this wouldve happened at high rpm.

Now to my options. My mechanic wants to install "modified" oil squirters that sit a little bit lower and shouldnt get clipped by the pistons, but my thinking is if everything should have been ok to start with, this shouldnt have even happened. Other options are to completely strip and rebuild the engine (as its still under warranty -- just!).

Just after some general feedback as to wether this is a common problem, or what I should do?

Any info would be appreciated.

[Ronin 09]

We had the sump off the car today (I also have pictures to show it can be done relatively easy without removing the engine, and also cheaper labour than removing the engine - R32 GTR)

Hi Amaru, sorry I don't have your answer, but do you want to start another thread with the pics to show how to remove the sump without removing the engine?

Cheers, hope you get the info you need

[N I B]

We have used around 25 sets of arias pistons in RBs this year and this has never happened so there is something odd happening.

[Amaru]

Will do, I dont have pictures of the whole process, just pictures showing the engine still in the car without sump. Its still a fairly heft process and will cost a pretty penny, but should be a few hundred less than full engine removal.

Will post tomorrow when I can get pictures onto computer.

[Amaru]

We have used around 25 sets of arias pistons in RBs this year and this has never happened so there is something odd happening.

My thoughts exactly. I was told Arias were not the best forged piston you could buy, but were still of pretty good quality for price. All of them have snapped off except for cylinder #1. Will try and get some photos tomorrow but any advice in the meantime would be appreciated.

[N I B]

Arias are as good as any piston you can buy and one off the world leaders inc top fuel.

[BNR32]

i dont think there is any question about the rebuild, if its under warranty, rape the bastards for all they are worth! I wouldnt want to re-engineer oil squirters that are an integral part of the engine, spray pattern etc etc wiil be affected if you extend their seating position.

TG

[wrxhoon]

maybe they installed the pistons back to front ? one side of the piston has like a cut especialy so they wont hit the squirters .

i have arias pistons im my rb26 ( 87 mm ) never had a problem .

[RB26zcar]

maybe they installed the pistons back to front ? one side of the piston has like a cut especialy so they wont hit the squirters .

i have arias pistons im my rb26 ( 87 mm ) never had a problem .

That sounds like the most likely cause to me without knowing any other details...

[GTR-Ben]

Engine builders fault... they are suppose to check for clearance with the squirters.

I have seen it happen before, but never when a good shop has installed the pistons.

[Amaru]

The pistons were installed the correct way around, and I can see the cut, but they still seem to have hit. When winding the engine by hand all the clearances seemed ok and they didnt hit, however I was told at high rpm they might have just breifly touched and thats what caused them to snap off.

Ah well looks like another rebuild on the cards

[wrxhoon]

The pistons were installed the correct way around, and I can see the cut, but they still seem to have hit. When winding the engine by hand all the clearances seemed ok and they didnt hit, however I was told at high rpm they might have just breifly touched and thats what caused them to snap off.

Ah well looks like another rebuild on the cards

did they use the correct pistons then ?

how do you know they were installed the correct way did you see them take them out ? the piston maybe correct on the conrod but the conrod put in back to front !

how much did the oil pressure drop when the broke off ? did it start knocking ?( the big ends ) if it did maybe you had incorrect clearences on the big ends then you wore them and then they may hit the squirters .

another reason the squirter may not be in the right position ( not in its grove like turned around a little ) , i have seen this in an sr 20 .

[ylwgtr2]

the squirter does not feed the big end....it cools the piston crown.....altho i assume you are getting at it would drop the oil pressure and cause the big ends to slap out???Id doubt that as even snapped of the hole is the same size

[Amaru]

did they use the correct pistons then ?

how do you know they were installed the correct way did you see them take them out ? the piston maybe correct on the conrod but the conrod put in back to front !

how much did the oil pressure drop when the broke off ? did it start knocking ?( the big ends ) if it did maybe you had incorrect clearences on the big ends then you wore them and then they may hit the squirters .

another reason the squirter may not be in the right position ( not in its grove like turned around a little ) , i have seen this in an sr 20 .

Most of what you are saying makes sense. All of a sudden one day, oil pressure dropped around 1bar at idle (at idle used to sit on 2bar and go to 4bar under hard acceleration, now it sits on 1bar at idle and goes to 2bar under hard acceleration) and the car has a 'knocking' sound to it, which ive asked the engine builder/mechanic to check multiple times and they say its nothing out of the ordinary - i have been worried about it though the whole engine runs -ALOT- louder than any other RB26's I know (it has a constant tapping noise, but it sounds like a faint knocking noise).

With the sump off I looked up into the cylinders and can see the cutout for the squirters, and they are installed the correct way around.

[Amaru]

the squirter does not feed the big end....it cools the piston crown.....altho i assume you are  getting at it would drop the oil pressure and cause the big ends to slap out???Id doubt that as even snapped of the hole is the same size

The hole isnt the same size, as a small example the feed for the oil squirter is "O" big and the actual hole it squirts out of is only "o" big. Will try and get a picture this afternoon.

[ylwgtr2]

so was the squirter spraying oil straight on the rod/bore?If so i assume the thing would have been blowing excessive amounts of oil....i mean a simple thing like too much bigend trust will cause an engine to burn oil but i imagine the squirter blowing straight on the cylinderwall, the smoke would be terrible

[ylwgtr2]

The hole isnt the same size, as a small example the feed for the oil squirter is "O" big and the actual hole it squirts out of is only "o" big. Will try and get a picture this afternoon.

So are they snapped off right and the base?I think they have a locating dowl so the cant be put on wrong....or maybe they didnt have the sealing washers on them?

[Amaru]

Hasnt been blowing smoke but it also has been using a bit of oil lately. It hasnt snapped off right at the base, about halfway along as they stick out, e.g

|

----//-----

Very rough picture of what they look like, the // is where they broke (assuming the piston hit the actual squirter upright part and its snapped half way along at the weakest point). The --------- part that sticks out is thicker than the actual squirter (|).

Just spoke to the mechanic and it looks like the engines going to be pulled from the car and stripped down... what started as a routine sump baffle installation

[BBQ]

What type of con-Rods did you use ?

[Amaru]

As said in first post, standard rods shot peened/polished