951 DI - Possible Cylinder Damage

[WaarrEagle]

2000 GTX DI. Engine blew (piston missing a chunk and lost compression) and had it rebuilt by SES. At approx 5 hrs in the break in process, I briefly went WOT and right after it started idling rough, even died a couple times. Further investigation revealed it will not idle on PTO cylinder alone (it should). Swapped everything imaginable and no change, so I bought a scope and checked out the cylinder. Compression is ~120 on both cylinders, but do I see a chunk missing in these photos? Curious what other folks see as I am not an expert with internal engine pics. But with compression it should run, right?

 

[GGuillot]

Baffling how you're still getting 120 on each cylinder. Compression will sometimes drop a little during break in as the rings settle. It'll improve some after 10 hrs or so. It kinda looks like it wasn't bored? the cylinder walls don't look that clean like it should from machining.. The piston look like they have a lot of black on top for 5 hrs. That piston piece missing? maybe the ports weren't chamfered properly causing it, since that's where it is. It's possible you have something else going on with the injection, not neccessarily the rebuild itself. But coming from SES, you don't know, there's been some sloppy workmanship coming from there before.

If it's showing 120 each cylinder you could probably still run it, but I think you've got something else going on with fuel delivery compounding what you see. Evidently, I think you're headed for a top end tear down and redo. Call SES and complain..

 

[mikidymac]

Call SES before you touch anything. You don’t want to void the warranty.

The pistons look really black for only having 5 hours a being a lean burn DI.

 

[WaarrEagle]

What causes black on the piston? Incomplete combustion? I believe the PTO cylinder has not been running right so that would make sense. I'll take a look at the MAG piston tomorrow for comparison.

I have tested compression several times since the WOT run and multiple gauges showed at or just slightly below 120. I have since busted the bendix (see other thread on that topic) so trying to figure out my next step. I can probably DIY the bendix but worried that will only get me back to where I was a few weeks ago with a motor that still does not run right.

 

[mikidymac]

Sounds like you never really figured out the original problem and just rebuilt the engine. Don’t feel bad as you aren’t the first and won’t be the last.

Typically on a DI it’s either a fuel supply issue or bad fuel or air injectors. Something is causing you to run lean and ruin pistons. You need to figure it out or it won’t stop.

 

[etemplet]

Yes, the engine is just a "pump", up and down is all it does. Did you send out the fuel and air injectors for servicing?

 

[WaarrEagle]

Fuel and air injectors were sent off for servicing. Fuel pump is good but fuel pressure bounces at idle, due to air pressure - see video here: LINK. Air pump tests good dead head, so I was stumped as to why. Air and fuel pressure regulators replaced, no change. Then the bendix blew. I'll take some more photos of both piston heads this afternoon and post for comparison.

My only other thought is to swap reeds. I have inspected the PTO reed several times but never swapped it.

 

[etemplet]

I'll be following. I got two DI's to renengine. They are impressive !!

 

[SabrToothSqrl]

I avoid DIs like covid, but I am curious to watch

 

[WaarrEagle]

Picture time!

Original cylinders, prior to rebuild, with ~225 hrs (hole in one of them):


Current MAG cylinder:


Current PTO cylinder:


Bonus of busted bendix:

 

[mikidymac]

Something is not right. Those cylinders look dry and defiantly seized.

 

[WaarrEagle]

Something is not right. Those cylinders look dry and defiantly seized.

When you say dry, does that mean lacking oil, fuel, or both?

 

[GGuillot]

When you say dry, does that mean lacking oil, fuel, or both?

I was looking at some of the pics, do you have specifics what was done? 'Rebuild' means different things to some people. I ask because in the pics like 725, 727 and others it doesn't look like it was bored out and fit to an overbore piston. The more I look closely it looks like a hone was done but not a boring to the cylinders. You still might have something else going on, double ck the oil injection system.

Ask SES if the RAVEs were trimmed....and what size piston was fitted. If it's stock bore piston reinstalled, I'd be upset.. Not saying it is, but I'd find out..

 

[WaarrEagle]

Update: Talked to Tom at SES and he confirmed damage based on the pics. Still under warranty so my next step is to pull the motor and get that fixed. He mentioned it was only slightly bored so plenty of "room" left. It will be a good chance to check out everything else and hopefully have better luck when it goes back together.

 

[WaarrEagle]

Working to get the engine out of the hull and found a bunch of metal in the exhaust pipe. From seeing this I suspect there is more damage than what I can see with the scope.

 

[etemplet]

That's a bad azz scope man !! Is that one you can plug into your phone?

 

[WaarrEagle]

That's a bad azz scope man !! Is that one you can plug into your phone?

You connect to it over wifi and can see the image on your phone/tablet. This is the model, <$50: Amazon.com: DEPSTECH Wireless Endoscope Camera, 5.5mm WiFi Borescope with 2200 mAh Battery, 1080P HD Semi-Rigid Snake Camera for iPhone, Android, Tablet, Sewer Drain Pipeline Inspection Camera(16.5FT): Automotive

 

[etemplet]

I bought one or my Android Phone but switched to apple. Thanks for the info.

 

[Titaniumboy]

I picked up this Lonove borescope with a 1080p 4.5”screen from Amazon the other day.

Borescope Inspection Camera, LONOVE Industrial Endoscope Camera 1080P 4.5" IPS Screen w/ IP67 Waterproof Snake Camera 6 LED Lights, Sewer Camera with Detachable Semi-Rigid Cable-16.5FT: Amazon.com: Industrial & Scientific

It is listed at $45.49 now, but it was $56 before a $20 coupon so I got it for $36. I still would have bought it at $46. I had been wanting a borescope for a long time, but the inexpensive ones designed to connect to your phone always seemed to have janky apps from janky Chinese companies . Those apps always seemed like an invitation to disaster and I just didn’t trust downloading those apps to my phone.

The nice thing about the unit I bought is that it has a dedicated screen. Now I don’t have to risk an expensive phone while using the borescope near the water or near a sewer.

I’ve already used it to retrieve a wingnut that I dropped into the bilge of my 1996 GTX.

 

[etemplet]

I picked up this Lonove borescope with a 1080p 4.5”screen from Amazon the other day.

Borescope Inspection Camera, LONOVE Industrial Endoscope Camera 1080P 4.5" IPS Screen w/ IP67 Waterproof Snake Camera 6 LED Lights, Sewer Camera with Detachable Semi-Rigid Cable-16.5FT: Amazon.com: Industrial & Scientific

It is listed at $45.49 now, but it was $56 before a $20 coupon so I got it for $36. I still would have bought it at $46. I had been wanting a borescope for a long time, but the inexpensive ones designed to connect to your phone always seemed to have janky apps from janky Chinese companies . Those apps always seemed like an invitation to disaster and I just didn’t trust downloading those apps to my phone.

The nice thing about the unit I bought is that it has a dedicated screen. Now I don’t have to risk an expensive phone while using the borescope near the water or near a sewer.

I’ve already used it to retrieve a wingnut that I dropped into the bilge of my 1996 GTX.

Man that is SLICK !!!

There is a monster that lives under each engine in Seadoo Jet skis. When you drop something they hide it behind shiznit, under shiznit and move it undetected 4' from where you dropped it. Sometimes they hide it in the holes in the foam on the sides of the ski. Them Bastages must DIE !! Cursing paralyzes them for a few seconds so if you curse a lot you'll find the missing part sooner. They won't show up on camera and are invisible to the naked eye. I have much experience with this.

 

[etemplet]

I picked up this Lonove borescope with a 1080p 4.5”screen from Amazon the other day.

Borescope Inspection Camera, LONOVE Industrial Endoscope Camera 1080P 4.5" IPS Screen w/ IP67 Waterproof Snake Camera 6 LED Lights, Sewer Camera with Detachable Semi-Rigid Cable-16.5FT: Amazon.com: Industrial & Scientific

It is listed at $45.49 now, but it was $56 before a $20 coupon so I got it for $36. I still would have bought it at $46. I had been wanting a borescope for a long time, but the inexpensive ones designed to connect to your phone always seemed to have janky apps from janky Chinese companies . Those apps always seemed like an invitation to disaster and I just didn’t trust downloading those apps to my phone.

The nice thing about the unit I bought is that it has a dedicated screen. Now I don’t have to risk an expensive phone while using the borescope near the water or near a sewer.

I’ve already used it to retrieve a wingnut that I dropped into the bilge of my 1996 GTX.

I just ordered one. Thanks Again !!

 

[WaarrEagle]

It has been almost a year but wanted to post an update. I still do not understand why the rebuilt engine would not idle on the PTO cylinder and was running so rough, so I pulled the motor again and sent it back to SES for another rebuild. It took a while, but I got it back and installed earlier this year. So far so good on the 2nd rebuild. I set the oil pump just a fraction ahead of factory to be safe and have yet to do any WOT pulls, but I am cautiously optimistic that the ski is finally sorted.

Also had to work through a non-working fuel gauge (re-seating connection at the MPEM fixed that) and a bad rectifier (12v low warning kept appearing), but both of those issues seem to be resolved as well.

A cautionary tale to anyone taking on one of these busted DI projects. I started this adventure in September 2019 and stopping tracking how much I spent on it long ago!

 

[etemplet]

Never add up the $$, cuts and bruises. Good Job !!