Payton Utzman

Ok so I had a machine shop do a small block rebuild on my 1994 5.8L, fast forward 2 years later and just two weeks ago drove the truck for the first time. Heard a weird tick so took it to the shop to have it checked out, they took off the oil pan and examined.... told me the engine was hydro locked and a rod was bent and a piston broke. They first tried claiming I poured gas down the spark plug hole, but I think they are giving up on that. They want me to bring the engine down and they’ll fix it... but at who’s cost? Now I’m in a dilemma because how can I trust the mechanic with being honest if they made a mistake, but if I take it farther apart they will claim I did the damage and pulled something out of the cylinder before bringing it to them. I’ve pulled the engine and stripped it down to just the intake manifold and valve covers. Now something I noticed with it on the engine stand, the rods do not appear new. They have Ford stamps on them and I can’t imagine them buying rods from ford.... but these are bigger pistons because the cylinders were hoamed. The rods have discoloration on them at the top near the position, blue like they got really hot. Had a retired mechanic take a look and he can’t imagine why they would get this hot.... unless the pin between the piston and rod is too tight. Also worth noting that when we stuck a camera through the spark plug we didn’t see anything on the piston but there was a roundish clean spot where there was no carbon buildup. None of the other pistons looked like this. I trust the owner of the machine shop, not so much the young mechanic who did the rebuild.... At this point I’m worried about all the other rods failing (less than one mile on this “new” engine) and the plan is to take off the valve covers tomorrow to take a look. Also toying with making an appointment to watch as the mechanic takes apart the engine. Looking for any input on the discolored rods and possible explanations... thanks from a kid just trying to get to college in two weeks!!

NFortin1966

Just a couple of observations here, and it could be just the pictures showing false information, but on the top picture, it looks like the rod is twisted and the top of the rod (where the pin slides through) has cracked and separated. It also looks like the top right corner (just before the pin) made contact with the counter weight of the crank. On the second picture, the arrow on the top of the piston indicated what direction the piston should be installed in. Most pistons that are directional will have the the arrow pointing up as the top and bottom of the skirt may be different for clearance reasons. Check to see which way the arrows on the other pistons on that same side are pointing. If that one is different from the others, then you have found the problem and know that it was installed incorrectly..

Payton Utzman

Yes you’re right, the counter balance was actually carving out the skirt of the piston. As far as the arrow and directionality of the piston I’ll check that out tomorrow. Thanks for the input!

sdmartin65

Take it back down to the machine shop and let them have the chance to make things right. You also need to be realistic on time frames. It's taken two years from rebuild to spot the problem and for this rebuild they might need more parts than before to build the engine. Most rebuilds the crank and rods are reused. Depending on the damage they might need to get a lot of parts or even another engine.

catch 22

OK, the discoloration is because your rods were heated to insert the wrist pins, had you PAID to have the pins "floated" you wouldn't see this (yeah some shops use a press to install wrist pins, that leads to other problems). The arrows are ALL supposed to point to the front of the engine. Yep the counter weight hit the piston skirt...….right after the rod bent and became too short. Why/how is there "carbon build up" if the engine only ran for a few minutes? Before you get into a pissing match with the machine shop.....just exactly how far did they build the engine, did they do the short block and you completed it or did they build the entire engine? Something smells fishy

Payton Utzman

They did a short block and I completed it. I added on intake and exhaust manifolds, fuel injectors, valve covers, timing chain cover, water pump, distributor and so on. I never touched the valves or heads. I also checked the arrows on all the pistons and they all pointed the same direction, forward towards the fan.

catch 22

The best thing to do at this point, and what the machine shop SHOULD do is fill the engine with water and pressurize it to verify coolant/water not getting into chamber/cylinder. Because the camera shows no catastrophic damage to piston, I would say that some kind of liquid got into the cylinder. I had a 300 6 cyl. Ford bend a rod while turning it over with the starter and lock up (looked just like yours).....because an employee was too lazy to do a cylinder leak down test (as requested) to verify my suspicions of a blown head gasket (which it was). At this point in time you and the machine shop need to work together to find the root cause of this.