RB26 rebuild problems (oil squirters)

[Sydneykid]

Something is wrong with the piston to centre of crank measurement. As Steve says the Arias pistons have the right cut out for the squirters. The squirters can only be installed with one orientation, there is a pin on the squirter body and a hole in the block. They have to line up when you assemble it, otherwise you can't screw the through bolt in.

So the piston is travelling too far down the bore, this could be little end bearing damage, big end bearing damage or bent conrods. I have seen one or more of these break a squirter off, I haven't seen all 6 though, that's unusual.

The broken bits of squirter have possibly been sucked up by the oil pick up and damaged the oil pump rotor. I suspect it will have all been trapped by the oil filter, but maybe not.

Bottom line, it really needs a full pull down and inspection and a proper rebuild. I would not consider anything less. Good luck and I would really like to know the final outcome

[BBQ]

Sorry my bad, Miss read the part about the rods... they put the rods in around the wrong way....

[DAN00H]

Hi Nik

Hope you get it sorted without too many difficulties... not good news.

[Amaru]

Thanks for that Dan

Just talked to the engine builder whos had a look at it, and its not actually the bottom of the piston thats hit the squirter. He says the pistons run a 5 thou clearance and when cold rattle around a bit in the cylinder, and its the side of the piston hitting the squirter. The car hasnt been started in a few weeks, and they used a screwdriver to move the piston across to one side and confirmed the side of it was hitting the squirter. Does this sound like a possibility?

[japtaxi]

amaru,

This might give you some more suggestions as to the cause..

http://www.tomei-p.co.jp/_2003web-catalogu...iston_rset.html

[Sydneykid]

Thanks for that Dan

Just talked to the engine builder whos had a look at it, and its not actually the bottom of the piston thats hit the squirter. He says the pistons run a 5 thou clearance and when cold rattle around a bit in the cylinder, and its the side of the piston hitting the squirter. The car hasnt been started in a few weeks, and they used a screwdriver to move the piston across to one side and confirmed the side of it was hitting the squirter. Does this sound like a possibility?

AAARGGGG, excessive piston to bore clearance. Sounds like this is going to be expensive to rebuild, either new pistons or cylinder liners. :headbang:

[Mik]

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

I think he is saying that when the squirter broke, the hole was much larger than it originally was (as the squirters are tapered), and this would cause a drop in oil pressure.

[fatz]

when i built my engine i had built the the bottom end and turned the negine

after roatating the full assemble one of the pistons hit the oil squiter cause i hadnt stuck it on the dowel had to steal one off a rb25

[Sydneykid]

I think he is saying that when the squirter broke, the hole was much larger than it originally was (as the squirters are tapered), and this would cause a drop in oil pressure.

Each squirter has a spring loaded valve inside that only opens when the oil pressure increases ie; when the rpm rises above idle.

[proengines]

Just to clarify things, I assembled the engine and just had a look at it about an hour ago.

The side of the squirter can touch the piston on the pin boss area if you lever the piston towards the front of the engine (the squirter is on the side of the piston towards the rear). When the engine was assembled, I dummied and checked the skirt to squirter clearance which is fine. (I have had Wiseco pistons for RB26's where the relief milled in the piston skirt wasn't deep enough and they interfere, which means having to mill the reliefs deeper, thats why I dummy them to check).

With the piston centred in the bore, there is also enough clearance between the squirter and the piston pin boss.

It's only if the piston moves right to the front side of the bore that the squirter touches the piston. The piston can move a fair amount sideways (as in front to back of the engine) as all piston skirts are machined slightly oval with around a .020"-.025" (.5mm) smaller diameter in line with the piston pin than across the skirts. The piston to bore clearance was .005" (5 thou) across the skirt which is where it is measured.

I've never seen this problem before but there is a first time for everything. It's just a matter now of fixing it.

To fix the problem it's a matter of machining something to give the clearance needed. It's a choice of machining the piston pin boss or machine the squirter. I think it would make more sense to machine the squirter slightly along one side rather than machine a piece out of the piston pin boss. The squirter is not under any load and it is only a matter of linishing the parting line from when the squirter was cast. I would prefer to do this than machine the piston at all as they are obviously highly stressed.

Really, it's up to Nik what he wants to do. The engine wouldn't have lost any oil pressure due to the broken squirters as the bolts that holds them in place have a plunger and spring inside that only lets oil to the squirters once oil pressure is at a certain pressure. Also, the conrods are fitted the right way around.

I just thought I'd clarify some things to save people having to guess. Theres no sense in trying to blame anyone else, ultimately I'm responsible and thats why I always give 12 months/20 000km warranty on my performance engines and will fix the problem.

[Amaru]

Hi Greg,

Just to clarify with you, I am extremely impressed and satisfied with the engine rebuild you did for me and I have mentioned this to Ed a few times now. Even after this small hiccup, all I can say is shit happens, and as you said yourself, its something you have never seen before, so we can all learn from this experience

I didnt come on here trying to point fingers or direct blame onto you or anyone else, just looking to see if anyone else had experianced this problem, and if so, why it happens and how to fix it

Ill be going to see Ed at 5PM this afternoon if you wanted to come along as well so you can explain in simple terms to me what went wrong

[Duncan]

top thread guys, and thanks especially to proengines for posting

[Sydneykid]

Just to clarify things, I assembled the engine and just had a look at it about an hour ago.

The side of the squirter can touch the piston on the pin boss area if you lever the piston towards the front of the engine (the squirter is on the side of the piston towards the rear). When the engine was assembled, I dummied and checked the skirt to squirter clearance which is fine. (I have had Wiseco pistons for RB26's where the relief milled in the piston skirt wasn't deep enough and they interfere, which means having to mill the reliefs deeper, thats why I dummy them to check).

With the piston centred in the bore, there is also enough clearance between the squirter and the piston pin boss.  

It's only if the piston moves right to the front side of the bore that the squirter touches the piston. The piston can move a fair amount sideways (as in front to back of the engine) as all piston skirts are machined slightly oval with around a .020"-.025" (.5mm) smaller diameter in line with the piston pin than across the skirts. The piston to bore clearance was .005" (5 thou) across the skirt which is where it is measured.

I've never seen this problem before but there is a first time for everything. It's just a matter now of fixing it.  

To fix the problem it's a matter of machining something to give the clearance needed. It's a choice of machining the piston pin boss or machine the squirter. I think it would make more sense to machine the squirter slightly along one side rather than machine a piece out of the piston pin boss. The squirter is not under any load and it is only a matter of linishing the parting line from when the squirter was cast. I would prefer to do this than machine the piston at all as they are obviously highly stressed.

Really, it's up to Nik what he wants to do. The engine wouldn't have lost any oil pressure due to the broken squirters as the bolts that holds them in place have a plunger and spring inside that only lets oil to the squirters once oil pressure is at a certain pressure. Also, the conrods are fitted the right way around.

I just thought I'd clarify some things to save people having to guess. Theres no sense in trying to blame anyone else, ultimately I'm responsible and thats why I always give 12 months/20 000km warranty on my performance engines and will fix the problem.

Excellent Greg, on RB30's we make up thin alloy washers that fit the oil squirters and moves them 1mm lower. Would that help in this case?

[GTRgeoff]

Don't be so stupid SK. That's way too easy and simple

Actually there shouldn't be any reason it wouldn't.

Great to see a quality engine builder standing by his product, and willing to explain the problem.

[proengines]

Sydneykid, we had a look at that today with some 12mm id aluminium washers, I'll try it tomorrow and see what difference it makes. Ive been trying to think why the pistons would move forwards and the only thing I can think of is maybe under really heavy braking (might be those brembo brakes... lol). I suppose they only have to touch once.

I rang the piston supplier today to ask if they had heard of this happening with any others using the same pistons and he wasn't sure but then not many have probably been apart yet either.

Regarding the rb30's, is there much metal to drill and tap to fit the squirters to them? I'm currently starting one for my own car and wouldn't mind fitting a set but heard they are a lot thinner below the gallery than a 20/25/26.

Oh, and thanks guys for the nice comments, I thought it would make sense to try to explain what happened, it might save someone else the same problem. (I'm still worried about the guy who wanted to rape me though...)

[ylwgtr2]

fantastic service from proengines.......i personally dont know many mechanics that wouldnt try and back pedal there way out of this one....can i ask is that the specified clearance for those pistons?have you ran this clearance before?

[proengines]

fantastic service from proengines.......i personally dont know many mechanics that wouldnt try and back pedal there way out of this one....can i ask is that the specified clearance for those pistons?have you ran this clearance before?

Off the top of my head, .004" is the specified clearance. I normally add .0005" (half a thou) when I hone them just in case one day it overheats and picks up. They use file back rings so this isn't a problem, even without file backs it would only add .0015" ring gap. I was talking to one of the guys from ACL pistons a couple of months ago and he was saying with their forged pistons (Ross currently makes their forged pistons for jap engines) you could probably run .0035" as long as you ran a good 5w30 or 0w30 synthetic oil.

The thing is, the clearances most piston makers give you are the minimum specified clearance that shouldn't cause any problems for them or you, not an absolute figure. The only problem with increasing the clearance too far is that the rings will lose some stability if the clearance is really big. with a forged piston though, once it warms up it expands and takes up most of this clearance, thats why they're noisy when they're cold and quieten down when the engine warms up.

By the way, once ACL/Mahle start producing forged pistons for jap turbo engines you wouldnt use anything else. Their V8 pistons are beautiful, run really tight clearances and are ultra strong. They do Subaru's and Hondas so far I'm sure, more to follow. 6 or 7 of the F1 teams use Mahle pistons so thats a pretty good recomendation.

[Sydneykid]

Regarding the rb30's, is there much metal to drill and tap to fit the squirters to them? I'm currently starting one for my own car and wouldn't mind fitting a set but heard they are a lot thinner below the gallery than a 20/25/26.

Hi Greg, yep you are spot on, fitting block mounted oil squirters to an RB30 is really a bitch. We have tested 2 engines for 12 months with ceramic coating on the piston crowns (Competition Coatings) instead of the squiters. Plus a few minor mods to the rod mounted squirters. Pulled one down for inspection and I couldn't tell the difference between it and another with squirters. Wear rates, piston hardness, crack test, sonic etc nothing showed up any different. Both engines run 600 to 700 bhp in competition, so they get a hard life. Both have decent size oil coolers and we only use Castrol Formula R Synthetic 10W60.

Hope that helps

[discopotato03]

Really good thread people , also pleased to see a workshop with principles . Am going to start a thread on RB30 pistons as its O/T here .

Cheers A .