2003 GTI LE RFI - Root cause of mag side piston failure...

[swannydoo]

Hi All, this is my first post and I'd like to start by saying a massive thank you for posting all the valuable info!

So... after cutting my teeth on a 1994 XP rebuild, I picked up a 2003 GTI LE RFI that has a bung front piston, it's absolutely trashed, but the rest of the machine is in immaculate condition. I've got new pistons, rings, bearings, pins, clips, gaskets etc... but I'd like some advice before just putting these in and having it blow again after an hour...

I understand from a lot of reading that the RFI's are notorious for breaking, I'd like to track down the root cause for the piston failure before popping in a new one and hoping for the best. I believe the engine is original bore as the wrist pins were cageless. (none fell into the crank case ;-)) The injectors spit fuel out on cranking, the crank seems to not have any play in it but some advice on how to check crank condition (in the boat) would be handy, I'm hoping there's a way to check this without removing the engine and cracking the case? (which I will do if you think that's what it needs, but... would save a lot of work if there's some way to check it in situ)

Things I've noticed:
- Front piston is absolutely trashed
- Cylinder walls have a tiny amount of rust and pitting (but no major scoring) (a little honing has removed all signs of pitting and glazing)
- PTO side of crank case has oil in it when i spin the crank, but the front side doesn't
- Some corrosion in water jacket area - is there a blocked hole? See images below
- Head has been trashed by the bung piston.
- RAVE on bung piston cylinder is stuck

Things on my list to do:
- Hone cylinders = done
- Replace fuel filters
- Replace all gaskets and seals in top end
- Check ohm reading on injectors and get them cleaned (I believe it should be 2.4ohms)
- Can i sand/grind the rough parts of this head or is it toast?
- Check fuel pressure

Any advice on what to check would be most welcome.

I've attached some pics below (have more if needed):

 

[Spider4real]

Looks like that engine failed from lack of cooling. The water jackets are plugged up solid with something (salt?). I also can see rocks and sand in there. Looks like someone forgot to flush the engine.

 

[mikidymac]

You need to have the cylinders measured to make sure they are within spec before just honing and installing new pistons.

I would verify that that cylinder is actually getting oil and send the fuel injectors off for cleaning and testing.

 

[swannydoo]

Thank you for the replies... Yes the water jackets are putrid, I left everything as is to get the best advice, I'll clean and flush every bit of the cooling system, I dare say there'll be more sand and rocks all though it.

looking in the manual, if I stick the new ring in the cylinder (between ex port and top) and measure the gap with a feeler gauge (manual says: 0.40-0.55mm .016-.022in), will this be enough to check the diameter of the bore is within spec?

If checking the ring gap isn't enough, I'll take the cylinders into my local shop to be measured and honed, having never done it before myself, and not having the tools to measure it, I'm flying blind...

Ok great, I've checked the manual and will test the oil pump is putting out 5.7-6.9ml each port at 1500rpm for 5 mins.

 

[mikidymac]

No. You need the cylinders measured with an actual bore gauge to determine if they are within spec.

 

[etemplet]

You're gonna need a cylinder bore. If those are original wrist pin bearings you may as well start fresh. Make sure the chamfer the ports after boring the cylinders.

I'd say you have an oil or fuel problem with the failed cylinder. Make sure you replace your oil lines and prime them. Remove the fuel injectors and send them to fuelinjectorman.com $25 each and you'll have good injectors ready to go.

Replace the fuel filters in the fuel tank canister... this is a must do.

When you get the RFI back running you are gonna love it !! Hit the button, they start right up, Warm it up good and have fun !!

 

[Poormanracing]

Front mag cover crank seal

 

[swannydoo]

Oil pump checks out fine, oil lines are immaculate, and oil is blobbing out nicely when spun by drill CCW, fuel filters should arrive in the mail by the weekend.

The failed cylinder measured, 3.238" or 82.245 mm - Which, coincidentally is exactly the first oversize bore diameter in the manual... Could this simply be the reason for the failure? Wear and tear to the maximum spec and pop! There's 250 hours on the clock.

I can swap my new standard bore pistons/rings for 0.5 mm oversize, but not 0.25 mm. In the manual it states 'Second oversize - not applicable" yet there are piston sizes 0.25, 0.5, 0.75, 1.0 mm oversize available.

Q. Am I good to get the cylinders bored out to suit 0.5 mm oversize pistons?

Seems like there's plenty of meat on the bone to grind out to 0.5 mm? (I can get 0.25 mm over pistons but they're about 3 times the cost + shipping (and shipping time from the US to Australia at the moment is looooong)

With regard to the head... (image above) Is it stuffed? Repairable? Most of the second hand ones online look the same... mag side is gouged and rough. I assume if i mill/grind/sand one side i'd need to do the same to the other...

Q. Do i need a new head, and if so, will the head from 787 carb engine fit - they look the same, but looks can be deceiving...

Also - There's no gaskets under the RAVE valves...? There's just a rubber ring embedded on the valve side, is this all that's required or should there be gaskets there?

 

[mikidymac]

Yes, at high hours and worn cylinders/pistons they can just fail.

Yes, you can overbore all the way to 1.00mm over but you will have to go with aftermarket pistons as Seadoo only went up to 0.25mm on the OEM oversizes.

I would not start swapping carb and RFI parts.

Yes, the RFI uses o-rings on the RAVE bases not gaskets.

 

[swannydoo]

Fantastic, thank you!