just had a 2.5l cdb engine built with forged internals. to be honest it sound more like a diesel engine when cold, at first i thought it was the big end bearings but the engine builder says its just piston slap and its nothing to worry about.the noise does quieten down a little when the engine warms but even over my load exhaust i can still hear it and its stating to get on my nerves now.has any body else had this problem from a newly built engine and is this going to cause me any problems in the future.

 

not sure about any probs you may have , but mine sound the awesome , with RCM big port heads , supertech valves , no piston slap at all , rev smoother than my old ej20..
i think it should not be doing that ...if the right piston, rings are builts/fitted correctly .

 

thats what i thought when i got the car back i really expected the engine to be very quiet as everything is brand new and not sound like its running with no oil in it.

 

i'd go straight back with it mate, you wouldn't buy a new impreza from the showroom with piston slap so why should this be any different. i feel for you as i had a garage rip me off rebuilding a mi16 engine for my pug 205 years ago

 

Some pistons do make noise before they get warm, but if it's still doing it when warm, I'd be very wary. Speak to the piston suppliers if the engine builder didn't supply them

 

I've just had a new EJ257 built with forged CP pistons and you can just about hear piston slap when cold but it goes once the engine has warmed up. All the pistons were matched to honed bores.

This is normal for forged pistons, in fact, the pistons aren't even round when cold, they're slightly oval until they get up to temperature. That's not to say that it should sound like a diesel engine though, the engine should be quiet once it's warmed up.

Has the noise developed or has it sounded like this all the time?

 

Has the noise developed or has it sounded like this all the time?[/QUOTE]

the noise has been there from day 1 the answer i got from him when he told me that it was only piston slap was, you should here the noise my own demo car makes.surely if theres any nocks or rattles on an engine then over time this is going to cause some problems.as for having a word with the piston supplier every time i have rung him for things he,s forgot about it and ive had to ring back or he,s been dealing with a customer and he will ring me back, but has he, no. to be honest the service ive recieved all the way through the build has been crap and the piston slap isnt the only issue ive had as its still not running rite either.

 

He doesn't sound like a reputable builder mate, to be honest. I assume you've paid in full for the work? If you've paid using a credit card you might be able to make a claim for a refund through the credit card supplier, otherwise you'll have to start proceedings through the small claims court.

First off, get an independant opinion from a specialist Subaru engine builder to see what they think. If they confirm that the work is shoddy take the info back to your builder and insist on a refund/rework. At the end of the day, if the builder was reputable, his work would be guaranteed and there wouldn't be an issue.

 

yes ive paid in full and then some but paid by cash, have had to book the car in somewere else to remap it properly as the map he did was rubbish,so will be letting them take a look at it to see what they think.

 

Sounds like the clearance on the pistons is too big.
Ask the builder what clearance he had. As a guide I've just had mine done to 3 thou.

 

Is it using much oil

 

yes had to top up the other day it had used a litre of oil in a week,thought it must have just burnt it with it being a new engine but just found out were its all gone,its all in my catch tank.ive had the oil catch tank on for around 18 months on my old engine and never had to empty it once had this engine in a few week and had to clean it out already,not only that the pipe thats vented from the catch can has pissed oil all down the side of my new engine,i might not be no expert on engine building but if oil is breathing into my catch can then doesnt that mean its blowing past the piston rings.

 

Yeah something’s not right.
How many miles did you do in the week?
I have seen a few threads in the past with 2.5susing too much oil. https://www.scoobynet.com/general-te...-you-burn.html
Here is one example that springs to mind if you read through it turns out the failure was the owners fault because of a badly fitted oil sender but it was using oil before it went bang. But no mention of piston slap.
I would take it back ASAP if they are a reputable company and you are reasonable (not shouting the odds) am sure you can get to the bottom of it, am sure they matched the piston size to the bores but mistakes can happen.
Keep us updated

 

going t give him a ring tomorrow as something clearly isnt rite and see what he says about it all.dont fancy him having to take the engine out and pull it apart again but then again i dont want a nackered engine on my hands in a few months time either.

 

I get no piston slap from mine & is not using any noticeable amounts of oil. something is very wrong.....

 

well i made afew phone calls to the engine builder today and after 3 calls managed to get through, only to be told that he was still on holiday until tomorow which didnt make me feel any better,anyway i was told that as soon as he comes in tomorrow he will ring me back.so when i got in from work i got some advice from another very well known engine tuner and was told basically it could be down to a few things, mainly the clearance of the bores for the piston is too big or it could be a faulty piston or set of pistons. so i will just have to keep my fingers crossed that i can get some joy tomorrow.

 

Some of the "drop in" pistons will make a little noise when cold but not a big issue. In saying that id imagine if yours is a full build then you would have had a hone and each piston matched to the bores.

 

yes it was a full build and as i believe each piston was matched to each bore, maybe it could be a faulty piston or so i guess i wont know until i get intouch with him and he takes the engine apart again.

 

hope it goes well for you mate!

 

Can we ask who the engine builder is.

 

Better built too loose than too tight....otherwise it wouldn't last very long at all.

Either way, its a clearance issue. That required clearance is down to the piston material used; Forged vs cast, hypoeutectic, hypereutectic and eutectic compositions. What exact pistons used would dictate the minimum/maximum required piston-bore clearances that would be acceptable.

Forged pistons with low silicone content will expand by a larger amount when hot when compared to one with a higher silicone content. This requires it to have larger piston to bore clearances to ensure it doesn't nip up in the bore at full load temperatures. The net result is it sounds like a bag of spanners when cold, and in extreme cases not that much better when warm either (although it should be quiet at idle after a good blast round a race track ).

 

ide rather not say who the builder is just yet until i have had a chance to speak to him properly and hopefully get this sorted out as it might be his fault but then again it might not.

 

how did you get on?

 

managed to get intouch with him last week and i took a ride down on saturday as i was having problems with my idle control valve which he fixed for me while i was there.he went through everything with me about the piston slap and the engine breathing oil.firstly he said the engine using so much oil wasnt acceptable and he was not happy about that. he wants to give it a couple more weeks to settle and if nothing changes he will take it back out and rebuild again at no cost to me.now as for the piston slap he says that is how the engine will be as that is how he builds them to allow for expansion off the forged piston under high boost.i feel a little better now i have had a talk with him and he guarantees me that if anything does go wrong with the engine that is result of his work then he will sort it with no arguments.

 

Ask him what clearance he's given you on the pistons.

 

i asked him this he said he uses 3 to 3.5 thou

 

That's not anything out of the ordinary. I always use 3 thou.

 

Now I'm worried cos I'm in the middle of building mine up at 0.0025" clearance on Wisecos, although that's their recommended gap. However, I have thought of something...are your pin offsets the right way round? Otherwise they'll rattle. Looking at my pistons, you wouldn't notice the offset in the pin hole location by eye unless you are actually concentrating - it's only 2mm one way rather than the other. But this is what makes them noisy or quiet apparently. The offsets need to be down on 1 and 3 and up on 2 and 4 IIRC as the crank goes round clockwise.

 

As above if you paid be credit card you get 28 days to do a charge back. All you have to do is phone your credit card company up tell them you have say 2k missing from your bank and would like to no where it's gone.
Then when they say it's gone to the robbing b-st--d who did the build. just say i no nothing off this.
It make no difference if you did sign any thing, you will get your money. Then he is 2k outa pocket not you. Simply but remember 28 days is cut off

 

O same aplys for cheque's 2 as long as you did not put cheque guarantee card on the cheque I.E on the back.