Rebuilds Gone Bad

[DanStokes]

I was reading the "when did you rebuild your first engine" thread, and it brought to mind "What Rebuilds Went Bad on Ya?".

I've had a couple. The most frustrating was probably the '73 (I think) Saab that belonged to a shop that my buddy owned. The goal was to fix it cheap and sell it. So I came over (hey, I'm the engine expert, right) and did a ring and bearing job on it. It ran a couple of hundred miles and the rods came back clattering (it had been sold). Pulled the engine back out, mic'ed the crap out of everything, all looked OK, so I decided I had a bad set of bearings. Reassembled the motor, reinstalled it - yep, back in 200 or so miles again. Sent the rods out for reconditioning and that cured it. I still haven't figured out how the rods could mic OK and not BE OK. The only thing I could figure was that the surface finish on the rods was wrong to hold the bearing shells in place, but the squish should be the main driver on that, and that measured OK. Who knows?

My only attempt at a SBC rebuild also went bad - maybe the reason I'm NOT wild about SBCs. All the bearings continued to fail in that one. I even found a junkyard 350 shortblock which failed the bearings without me ever touching it. Somebody said that I likely got a Pontiac distributor and that the oil galley seal area was incorrect so oil didn't get to the bottom end. No idea if that's correct. It was my bros truck, and he has less patience than I do, so he dragged the truck off after the 3rd. try so I never did resolve this one. Because it was unsuccessful, I continue to claim that I have never rebuilt a SBC.

Just so you don't think I'm a total idiot, I need to say that I HAVE rebuilt a BUNCH of engines successfully - usually weird-os.

Later
Dan

[VTJUNK]

Re: Rebuilds Gone Bad

I've blown up some that other people built, but only had one blow up that I rebuilt, but it was my fault completely.

On a SBF, I put Trick Flow heads on it and didn't check piston/valve clearance. Ran it all summer, ran real strong, then one day, in 3rd gear, pushed the clutch to grab 4th @6500 or so and the thing locked up tight. Towed it home, pulled a valve cover off and the rockers were loose on #2. Pulled the head and found the combustion chamber destroyed, int. valve head snapped off and stuck back into the head, piston shattered and gone. Rings were around the crank, cylinder wall was cracked. I pulled the intake (victor jr) and tipped it upside down and all these small pieces of piston came out. Parts of the piston even made their way into the cylinders on the other side of the motor. Expensive lesson to learn. I now check and recheck tolerances.

I brought the head to a local shop and it was repaired, but those sit on the shelf, I never have reused them yet.

[L98camino]

Re: Rebuilds Gone Bad

I was working in my buddies shop while in college he asked me to finish a rebuild on HIS buddies 300ci straight 6 Bronco. I put the engine back together and set it back in the truck and hooked everything up. Hit the starter and it fired right up! I immediately shut it down because the engine had a nasty knock! After much speculating and gnashing of teeth I did a compression check, #1 cyl. was dead. Long story short, pulled the head and rotated the crank by hand noticed a lump in the forward side of the #1 cyl. wall! The lump lined up perfectly with one of the water pump bolts. The bolt was too long and had pushed in the cyl. wall from inside the water jacket.

Result: All the rings broken, piston scored, cyl. had to be bored and sleeved. Had to disassemble the entire engine and clean out all the metal.

Aftermath: Had to work for free for a couple of days to pay for the damage (and take the ribbing for the rest of my life!)

Lesson: If the bolt starts to tighten before it seats, STOP!!!

[fabricatordave]

Re: Rebuilds Gone Bad

that is a classic 6 cyl ford thing .seen it done more than once water pumps come with a warning about the bolt lenghts

[Huskinhano]

Re: Rebuilds Gone Bad

I was going to night school for electronics, a guy I got friendly with had a 70 Camaro with a 402. He use to like to drive fast, like 100 MPH when he went to work. On one of his runs, his engine sucked up some of the plastic off the cam gear into the oil pump screen and spun a rod bearing. He was one of those guys who shouldn't be allowed to own tools. He took the motor apart in his basement and didn't know how to put it back. His parents where getting on his case. I offered to help. Upon in spection, I told him that the crank needed to be cut and the rods resized. He got the crank cut but wouldn't get the rods resized despite me insisting it needs to be done. He told me he didn't have the money so and had to have the motor back together. I tried to clean the rod up the best I could, removing what was left of the bearing from the rod. All of a sudden he had money for a new cam, headers and a carb....go figure! Any how, when I started the engine, all was quiet for the first few seconds and the cam broke in just fine but he had a real nice rod knock....wonder why?


I walked away from it since I did it for free and he wouldn't listen to my advice. He ended up having to pay someone else fix it right, the way it should have been from the start. Why is there always enough money to do it a second time but not the right way from the start?

[Fordplay0621]

Re: Rebuilds Gone Bad

I was helping my Buddy in Little Rock AR finish his 68 Camaro. We went to pick up the Finished Engine and went home to Install it. Everything fit great, started the first time and drove outstanding. within 100 miles the Car was limping back on Base. We pulled the Engine and found that the notch on the Pistons were facing the wrong way. Fought with the Engine Builder for a Month to redo the Engine. It was back on the road for the Summer and never had another Problem with it.

[TheSilverBuick]

Re: Rebuilds Gone Bad

Sadly my last engine was the one to not do so well :-\ Basically it was a garage rebuild (rings and bearings), none of it saw the inside of a machine shop (possibly the first reason of many smaller issues). It started ok, had problems there with timing, eventually eating a distributor gear, why I don't know. It started picking up distributor gear pieces into the oil pump and seizing the oil pump up. After destroying the second oil pump (I hadn't moved the car yet) I pulled the oil pan and cleared out the pan, oil pump and pick up passages, but the damage was done. I was finding metal in the by-pass passages, and even proping the by-pass passages open :-\ Got about 100 miles out of the engine before it spun some bearings. Engines out now and going in for a through machine shopped rebuild and I hope for a lot better next time around, I have another crank and set of rods in the basement ready to be checked and balanced

I think a possible secondary cause of the engine failure was the engine had spun a rod bearing, and I got a rebuilt crank for it but did not check the rods out past measuring them out, so I'm not positive if metal or bad rods were the true cause of the failure. Can't win them all.

[L98camino]

Re: Rebuilds Gone Bad

that is a classic 6 cyl ford thing .seen it done more than once water pumps come with a warning about the bolt lenghts

Yeah, I found that out after the fact! I chalked it up to "lesson learned". I was young and dumb at the time (now I am older and still dumb :D)and getting paid shop time. Now I have the patience to stop and look the situation over before I make the mistake.

I guess the point is that it is the smallest and simplest mistakes that cost the most time/money!

[squirrel]

Re: Rebuilds Gone Bad

got a PAW rotating kit for a mopar back in the 80s...it took a year or two before the bent connecting rod ate up the bearing.

[smallblockjay]

Re: Rebuilds Gone Bad

I've got two that I screwed up.

One was the same engine I mentioned in the first engine thread. 305 SBC. I thought it was a 350, but when I got it on the stand and pulled the heads, it was very obvious it wasn't a 350. I got a re-ring kit for it and replaced the rings and bearings. The cylinders still looked good and it probably could have gone right back together as it was, but I did the rings and bearings anyhow. I also got a little cam for it and a new timing chain. The timing chain had a 3-key crank sprocket for +4 degrees, straight up or -4 degrees. I tried to get fancy and advance the cam 4 degrees. Long story short, I did not put the cam in advanced 4 degrees and it was not even close to were it needed to be. When I tried to fire the motor up for the first time, it didn't go so well. After fighting with it for a while, I pulled a valve cover off saw all the intake pushrods were bent. Pulled the heads and all the intake valves were bent. I knew what the problem was at that time, took the front cover off and put the cam in straight up, new lifters and pushrods, put it all back together and it fired right up. I sold that van and saw those people driving it for years after, so I guess it ended up OK.

The second screw up was a brain fart. 350 SBC. Don't torque a 4 bolt cap down unless you're certain the little arrow is pointing toward the front of the motor. It will break the cap, requiring a new cap and alighn honing the block. BTW, I built that motor when I was 18 or 19 and it still runs. I hear the truck is trashed, but the motor still runs.