[rednexx]

I had another thread that went to this problem. I recently pulled my used motor that I installed in my motorhome. It had 185000 miles on it. It's an 89 7.3 idi with an aftermarket ATS turbo on it. From what I can assume, it was put on the original truck fairly early on. It was a F350 flat deck, special order built for the customer. The clutch had been changed to a Luk solid flywheel and the tag was still on the tranny. The waste gate rod has never been tampered with (ie no excesive boost levels).
When I installed it I put a boost and egt gauge in to monitor the vitals.
Boost - 7psi
EGT - max 1150 climbing mountain passes.
Compression is between 400 and 450 on all cylinders cold

Now to the real problem. I shoehorned the motor out to fix some oil leaks (external from the head gaskest) and some water leakage/useage. Once I got the heads off, I see that all 8 pistons are cracked about an inch long and all in the same place.
What I'm wondering is,
-how common of a problem is this
-how much longer would it run the way it was
-Any comment or suggestions
I'm looking at a $6000 bill to do a long block in a recreation vehicle.
Here's a couple of pics of the pistons.
Thanks for any or all input.

 

[chuckster57]

I realize the pistons are toast. But if the cylinders mic out okay- no taper and out of roundness or excessive wear, why can't you drop a set of pistons in it with new rings and bearings? For that matter can't you rebuild it yourself? I would think it would be considerably less, even with the machine shop work.....Just my opinion

 

[rednexx]

That's what i'm thinling too. Just give it a hone and put some new pistons and rings in.
I haven't mic'ed the holes yet, but there still are some hone marks there. I scared like hell about his whole cavitation problem with these motors, so that's another thing in my mind. I was losing/useing? 1/2 gallon in 300 miles with no vissible leaks.

 

[chuckster57]

I understand the concern about cavitation. maybe sleeves...still cheaper than a long block, as long as the machine shop knows how to do it right.

 

[Foz]

The same thing happened to me. I took mine apart investigating a head gasket leak. The problem is the early non-turbo engines don't have turbo-rated parts in them (pistons, rods and valves) to handle the increased pressures that a turbo provides. You could just replace the pistons and get another 185k miles out of the engine, or rebuild it to turbo specs (that's what I did).

 

[macmaniac1]

rebuilt with turbo stuff!

 

[Bill1013]

EGT - max 1150 climbing mountain passes.
Compression is between 400 and 450 on all cylinders cold

Where is your pyrometer mounted, before or after the turbo ? From all the post's on here it should be mounted before the turbo to give the correct or close true EGT's.
If the exhaust size has not been increased, That could be a problem.
Call Promar Promar Precision Engines 800-422-6022 they have turbo'd long blocks at $3099 now. I got one two year's ago and am very satisfied with it. If they block out the web site, email me [email protected] and I'll send you the web site. My shipping was free both ways, don't know about Canada, and all the taxes you guy's have to pay.

 

[rednexx]

The probe is installed pre turbo just into the y pipe where it bolts onto the drivers side mainifold.
The prices i've been getting for long blocks are $6-9 grand. I know a fellow that rebuilt his and had all 8 cylinders sleeved at a shop. Just that cost $2000! Start adding new parts (pistons, rods, bearings, head work, etc) and you could be into some big bucks.

Bill1013, thanks for the link. I'm going to give them all call and see what it will cost to get one up here.

 

[asauer]

rednexx- I will be running my motor with the cracked pistons anyway- only time will tell how it'll hold up, but I'm sure you're wanting to fix that thing ASAP, so I won't be much good for a guinea pig.
$6-9k is crazy. If you need a replacement motor I can find you at least 5 used ones around here, if you make the drive lol.
For that price, you could have a twin turbo'd 12V Cummins in there- transmission and all.

 

[rednexx]

asauer, I'm toying all kinds of ideas at this point. I've got a toyhauler to haul the goodies around, so i'm not in a huge hurry at this point.
I had a customer come in and he happened to have an aftermaket banks system on his truck. I told him my problem and how I came to finding it. We looked at the back of his motor and it and the tranny and underside of the truck were all covered in oil. I guess he didn't like the look of the inside of my motor, so decided to go trade it off ASAP. Maybe this is more common than we think. Like I posted earlier, I only tore it down to fix oil leaks, not runability problems.

 

[asauer]

Hmmm, that's very interesting.

 

[crashnfarmer]

The 7.3 out of my parts truck had 6 of the 8 pistons broken in the exact same place as yours, but I was assuming it was from the gasoline that the previous owner filled the front tank with, but maybe not.

 

[rednexx]

Update

OK, I've looked around at rebuilt long blocks, parts to put mine back together, and used motors.
I have a line on a factory '94 turbo motor complete (drop in with complete turbo system) with 160,000 on it for $1500. The problem is, it's 5 hours each way just to hear running.
I would like to do some tests on it before buying, but...he will ship it for that cost. I've seen pics of regular valve cover leaks and so, but not sure where to go with this one. Mine ran like a top until I pulled it apart to find disaster.
Any or all input would be great!

 

[hotrod220257]

my 2 cents nothings out of place and it runs fine so new head gaskets and save up for a new engine when the time comes then its not 2k out of pocket in one weekend and with those cracks itll still go a while without issues when you find running problems then go get that new engine and swap it in then sell the old one locally (not here we dont want it) lol and make some money back

my truck just hit 600 no issues so far

 

[hesutton]

No offense to anyone, but the idea of you running the motor with 8 cracked pistons is ridiculous!:nono: It's not if ........ but when you will completely destroy that motor. There is no way I would trust that engine for a trip to the freak'n Quik-E Mart, much less a long trip in a motorhome.

The coolant useage may be the cause of the piston cracks. If the cylinders where eating coolant.......and it was a significant volume.......this could crack those pistons. Liquid is not compressable and somethings gotta give. It this case, it was the pistons. I've seen this in the past with a poorly functioning homemade water/meth injection system.

Plus, what EGT's and Boost did this motor see in it's life? I those gauges where not used, some of that damage may have occured from excess EGT's/Boost.

Rebuild it. Otherwise........you will have a useless boat anchor on you hands.

Heath

 

[rednexx]

All excellent points! That's the reason it's not going back together as is. Like posted above, it's not if...but when it comes apart.
The idea of water causeing the cracks has merritt, but to leak on all 8 holes and create cracks in the exact same place and shape seems unlikely.
Wide open throttle, climbing for 10 minuets - 1150 max EGT (pre turbo) and 7 psi boost.
I have a line on a 94 factory turbo motor complete (alternator to flywheel including turbo system and ac compressor) to drop in for $1500. If compression and leak down tests pass, I will be picking it up and doing head gaskets prior to putting it in.

 

[hesutton]

The same thing happened to me. I took mine apart investigating a head gasket leak. The problem is the early non-turbo engines don't have turbo-rated parts in them (pistons, rods and valves) to handle the increased pressures that a turbo provides. You could just replace the pistons and get another 185k miles out of the engine, or rebuild it to turbo specs (that's what I did).

I'd seriously doubt the turbo was the cause of your failure unless you were running the turbo blind (i.e. no boost gauge or pyro). W/o these gauges, you can kill the motor without knowing it. The headgaskets (like above) probally leaked coolant into your cylinders and thus the cracked pistons.

Thousands of guys have turbos on these IDI's and rarely do you ever see cracked pistons. Look as THESE PISTONS. They are from '88 7.3 running 18-19 psi, for 68,000 miles on a 225,000 mile motor. Not a single crack and that is way more boost than the ATS, BANKS, or Hypermax kits will provide.

Heath

 

[asauer]

I don't think I'm rediculous for putting the motor back together as is- it's simply not worth throwing money into the wind to spend $3k+ on doing this motor the right way, when there are so many other motors out there.
There is no way the pistons are cracked from coolant- if so, the combustion chambers would have been wet...which they most definitely were not. The motor would have run terrible and smoked if coolant were getting into all eight cylinders.

The pistons cracked from heat- it's as simple as that.

 

[rednexx]

I agree with your diagnosis asauer. I've had some feed back from a factory tech, and he seems to think either the piston squirters are plugged, or it got way too hot.
I would put it back together for an around town truck, but for something that takes me 100's of miles away from home.....I just don't want to take that risk and be at the mercy of whatever town i'm in.
BTW, do you have yours back together and running yet. I'm really curious to how long it will stay together. I get lots of opinions on doing that or not also, but going to take a safer route (I HOPE).

 

[Foz]

Thousands of guys have turbos on these IDI's and rarely do you ever see cracked pistons. Look as THESE PISTONS. They are from '88 7.3 running 18-19 psi, for 68,000 miles on a 225,000 mile motor. Not a single crack and that is way more boost than the ATS, BANKS, or Hypermax kits will provide.

Heath[/quote]

I don't mean to be argumentative, but Ford did put more robust parts into the turbo engine, so it is a possibility. It wouldn't surprise me at all if many of the earlier engines with aftermarket turbos have fine pistion cracks, I would actually suspect that many do. Had I not taken my heads off for the headgasket, I wouldn't have known either because the engine ran fine. Your reference to the 19psi pistons sounds/looks good (and may very well be true) however, that came from the DPS website and he doesn't have the best following. I do like the heat theory though, and perhaps my and others issues are due more to heat because of aftermarket turbo/fuel turn-up performance tuning? I didn't have a coolant issue, my passenger side gasket had a small leak from the number 3 cylinder towards the intake manifold causing the tick-tick noise. I bought my truck used from a Ford dealer with 80k on it, so I don't know when the turbo was installed or how hot the previous owner ever got it.