engine gurus help please

L

Ls10

New member
so I refreshed my motor. when I bought it ,it was running ok but had blowby. a friend had a set of stock nos pistons. I wasn't looking to sink a ton of money into the truck because I already got royally screwed when I bought it. so I put new pistons,rings,and bearings. old bearings looked ok for 80k miles. I measured everything to make sure it was all in spec,even plastigauged it after and it was all right on the money. was very generous with assembly lube. it ran great,had great oil pressure. last night I had put about 100 miles on it so far and I did a few boost pulls,not long at all and at 14psi everything seemed fine. this am I took it to work, got on it a few times and noticed it didn't feel as strong. afr is 10.0 or richer (afr gauge only goes to 10.0) and had zero knock. when I got to work I noticed oil pressure was about 10 psi at idle and about 18-20 at like 2k.......but it was also knocking a bit. I noticed metallic in the oil so I got it towed home. when its cold I get almost no knock.......the engine is coming out sat morn to inspect.....what im wondering is what the hell could have happened? it was all mint when I put it together. ive built several motors before and all were great....so im stumped
 
dgoodhue

dgoodhue

BuSTeD 4.3
Re: engine gurus help please

I wonder if the pickup tube fell off the oil pump.

Btw 10:1 afr is way too rich. Being overly rich like that can cause issues as well but it's not the cause your low oil pressure.
 
gringo76

gringo76

New member
Re: engine gurus help please

depending on how rich it went and how long you drove it like that could have washed the oil out with gas and started tearing up the bearings. 10-1 afr or lower also make it seem like a pig.
 
L

Ls10

New member
Re: engine gurus help please

When cruising it runs very lean....to the point of breaking up. It has a turbotweak chip and 60# injectors. There was only a few wot pulls. Oil doesn't smell like fuel
 
gringo76

gringo76

New member
Re: engine gurus help please

ah well if there is metal in oil , gotta come out anyways. did you log is by anychance when is was going pig rich/lean? that would probably aim you in right direction as to the problem.
 
L

Ls10

New member
Re: engine gurus help please

I don't have a way to log at the moment,im just using a snap on scanner to watch knock and stuff. I noticed my iac counts a little weird,so I'll prob replace that. And I'm assuming the tune in the chip just needs a little tweek. But I don't think either of those things are what wasted the bottom end. I'll update and get some pics sat when I get it out......good at it by now,so should only take a couple hrs hahaha
 
Don W.

Don W.

Stab it and steer it
Re: engine gurus help please

Bet you a berger you took out one or both center main bearings. Maybe worse as in all 4. That's why you have no oil pressure to speak of. As to why, hard to say but I suspect knock. Eric's chip will flash the CEL when it detects knock. Did you see that? My experience with his chip is at that point the chip is already pulling (retarding) spark almost in the double digits. Way to much IMHO. Damage has probably already started. Again just my opinion. With all due respect to Eric, he has done well by me, a data logger is a must so you can watch what's happening.

And why it was running so rich needs to be figured out as well.
 
L

Ls10

New member
Re: engine gurus help please

Don W. said:
Bet you a berger you took out one or both center main bearings. Maybe worse as in all 4. That's why you have no oil pressure to speak of. As to why, hard to say but I suspect knock. Eric's chip will flash the CEL when it detects knock. Did you see that? My experience with his chip is at that point the chip is already pulling (retarding) spark almost in the double digits. Way to much IMHO. Damage has probably already started. Again just my opinion. With all due respect to Eric, he has done well by me, a data logger is a must so you can watch what's happening.

And why it was running so rich needs to be figured out as well.
Click to expand...

I have a snap on scanner on it and there was zero knock
 
L

Ls10

New member
Re: engine gurus help please

Yeah I had zero knock......but I just started it and tapped the block by the sensor and it stayed on zero........sooooo that's not good. I didn't hear any pinging so I really hope I didn't wreck the new pistons as well
 
L

Ls10

New member
Re: engine gurus help please

so I tore the engine apart today, all bearings are good except the two center mains. im going to replace all the bearings because some have small pits from the metal floating around. im not going to risk it over $50. im assuming my knock sensor went bad and it detonated itself to death......or just got bad bearings. I don't know but at least it wasn't catastrophic
 
R

robertmee

New member
Re: engine gurus help please

Don W. said:
Bet you a berger you took out one or both center main bearings. Maybe worse as in all 4. That's why you have no oil pressure to speak of. As to why, hard to say but I suspect knock. Eric's chip will flash the CEL when it detects knock. Did you see that? My experience with his chip is at that point the chip is already pulling (retarding) spark almost in the double digits. Way to much IMHO. Damage has probably already started. Again just my opinion. With all due respect to Eric, he has done well by me, a data logger is a must so you can watch what's happening.

And why it was running so rich needs to be figured out as well.
Click to expand...

Give that man a burger
 
L

Ls10

New member
Re: engine gurus help please

When I took the motor apart the first time the two center caps looked like one was installed backwards,but the bearings looked great. So I installed the caps the way they came off. Thanks Dave I'll give the crank a runout
 
L

Ls10

New member
Re: engine gurus help please

DaveP said:
Damage the center mains to the point you hear knock in 100 miles? With no audible knock, with no Knock Retard???

Something doesn't make sense. There must be more to it.

I had a 4.3 begin to make bottom end knock about 500 miles from new. Right about 1000 miles, I got on it pretty hard on an on-ramp, and by 20 miles later it was knocking to the point I abandoned the trip and babied it home, expecting it to go BANG at any moment.. It had spun a main, and one con rod bearing was toast. Long story, I won't go into, that engine was assembled with the two center main caps transposed. The clearance was correct, but the mis alignment caused problems.

My red/gry blew the waqstegate hose off the compressor housing, and would hit 30+psi. The knock was incredible. Did it to it 3 times in about 200 miles before I gave up, pulled over and fixed it. Took about 5000 miles before it was knocking badly enough, and had low enough oil pressure that I knew I had hurt it. Had to turn the crank, #1 main was the worst, but all 4 were pretty bad.

Point is that to do this in 100 miles, something is wrong. It is more than inaudible knock. At the very least, check the crank for straightness by placing the #1 and #4 bearing shells in the block, lay the crank in, and rig a dial indicator over #2 then #3 mains and check for run-out. I would also recommend using methods other than plastigauge to check the clearance.

Checking costs nothing. Check everything, because 100 miles is really quick. Out of the several hundred engines I've assembled over the decades, I've had a few go together wrong and had trouble. But not in 100 miles.
Click to expand...
It looks like my knock sensor is bad.....i couldn't get it to trigger by tapping the block next to it. It was replaced prior to me and when I went to remove it it was on so tight it was spinning the top part and the body was staying stationary. I had to use vise grips and a breaker bar to get it out...... it also has a flow disaster muffler, no tailpipe and super squeaky rear window......i didn't hear any pinging at all.......buttttt who knows
 
L

Ls10

New member
Re: engine gurus help please

DaveP said:
Damage the center mains to the point you hear knock in 100 miles? With no audible knock, with no Knock Retard???

Something doesn't make sense. There must be more to it.

I had a 4.3 begin to make bottom end knock about 500 miles from new. Right about 1000 miles, I got on it pretty hard on an on-ramp, and by 20 miles later it was knocking to the point I abandoned the trip and babied it home, expecting it to go BANG at any moment.. It had spun a main, and one con rod bearing was toast. Long story, I won't go into, that engine was assembled with the two center main caps transposed. The clearance was correct, but the mis alignment caused problems.

My red/gry blew the waqstegate hose off the compressor housing, and would hit 30+psi. The knock was incredible. Did it to it 3 times in about 200 miles before I gave up, pulled over and fixed it. Took about 5000 miles before it was knocking badly enough, and had low enough oil pressure that I knew I had hurt it. Had to turn the crank, #1 main was the worst, but all 4 were pretty bad.

Point is that to do this in 100 miles, something is wrong. It is more than inaudible knock. At the very least, check the crank for straightness by placing the #1 and #4 bearing shells in the block, lay the crank in, and rig a dial indicator over #2 then #3 mains and check for run-out. I would also recommend using methods other than plastigauge to check the clearance.

Checking costs nothing. Check everything, because 100 miles is really quick. Out of the several hundred engines I've assembled over the decades, I've had a few go together wrong and had trouble. But not in 100 miles.
Click to expand...
And do you know the crank bearing clearance by any chance?
 
L

Ls10

New member
Re: engine gurus help please

Tangs are both on one side and arrows forward.....i dropped the block and crank off the have it honed and cleaned. Just talked to the shop. He said he took the crank out when it was honed and cleaned......he said the mains looked ok so he put them back in......i was originally told they were new bearings.........so I think I just solved that problem hahaha. I guess if you want it done right you need to do it yourself. I did the rods and pistons and they look perfect
 
L

Ls10

New member
Re: engine gurus help please

DaveP said:
So you didn't put the crank in, or check it, or anything else? So the worn bearings may have been left in it by your "machinist"? Time to find a new guy.

There are a zillion operations involved in evaluating, machining, and assembeling an engine. Many of these operations require specialized equipment or knowledge. Even frequent builders like myself don't have these resources available to us, so we have to sub these operations out. I had good success with my guy because he KNEW that EVERYTHING he did was going to get rechecked when I got it in my shop for assembly, and WAS. If something wasn't right, he knew it was going to get caught, and be coming back, and I wasn't going to be happy because he wasn't cheap. (I now use a different guy, and the new guy's prices are about half of the old guy's were 30 years ago!). So I know he double-checked everything before he released it to me. We had a good working relationship. He made money, and my clients got good engines that ran smoothly, didn't leak, and were reliable over long terms.

Out of literally a couple hundred engines we did together, there were only 3 failures I can recall, all involving main bearings and clearances. The guy that ground his cranks frequently got the journals just a tad too big, and the clearance was too small. I'd bitch and bitch, and nothing changed. I quit having cranks ground unless absolutely necessary. The final straw was I lost the bottom end in a 502 in a Scarab (marine engines run at high output for extended periods) and it cost me about 5 grand to fix it. I bought a brand-new crank from Chevrolet. My guy found a new crank shop that could get the journals on-size within the specs I wanted. No more failures.

You iust don't know unless you check it yourself. If you don't, you're guessing and hoping.
Click to expand...
Yeah. I popped the main caps off just to look,they seemed ok,but I wanted to make sure the crank was ok,and I wanted to have the journals polished so I dropped it off with the crank in it. He said bearings were going to be replaced,but now he told me they looked ok and torqued it back down. I guess I should have looked......just felt like he was better than that
 
L

Ls10

New member
Re: engine gurus help please

I'm going to do a runout on the crank and make sure it's ok.......is there an acceptable limit or should it be exact zero? I did a google search just to be safe and oreily auto has one for $196 that can't be right can it?
 
L

Ls10

New member
Re: engine gurus help please

DaveP said:
The two slots for the tangs on the shells must be on the same side. You can't change the side the tang is on in the block, so put the cap on with the tang on that side too. There is an arrow with "F" next to it. Arrow points "Forward". These caps are also numbered at the factory. Almost always next to one of the bolts. If an engine has been disassembled, sometimes there are two sets of stampings.

On my deal that blew up in 1000 miles the engine had been previously worked on. (It was a Typhoon block). When I took it apart, #2 and #3 main caps were in the opposite locations. I suspected that the block had been line-bored, but wasn't sure. When I had the machinist that I had used and trusted for almost 40 years go over the engine, I mentioned this to him, and asked him to pay attention to the main bores, because I didn't trust it. He gave the block back with the instruction "put the caps on the way they're supposed to be". Ok, I did. And it blew up in less than 1,000 miles. He was wrong. He obviously didn't do what I trusted and paid him to do: Check it!

You need to figure out this main bore deal.
Click to expand...

And by tang you mean the notch for the bearing? Both notches on the block and cap are on top of each other. Is that correct?
 
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