454 Head back on engine started #7 piston noise

[trop-a-cal]

Now with full compression on both heads the 43,000 mile 1997 454 vortec has the same noise that it had prior to it shutting down completely. The noise was checked by removing spark plug wire and hearing the noise change. So off comes the pan and a check of the bushing on the piston for signs of it spun or a piece of the distribution worm gear stuck in the oil intake at the bottom center of the rod cap. This noise occurred after a slight ticking started back in New Jersey in September. It progressed to a knock South Carolina. It was preceded by a pinging in New Jersey, just after a 55 gallon fill up. That pinging we think was the antifreeze in the 3 and 5 cylinders just in front of the 7 on the right bank. It caused the distributor gear to grind on one side and perhaps drop some metal down to the pan where it got hung up in the #7 bushing as it was dropping down the oil throat of the rear mounted distributor which is just above the # 7 piston. We are going to check all piston bushings and torque on the piston caps when pan is off. All metal and other particles will be cleaned from the pan and the oil pump intake will be checked for metal stuck in the screen, which pumps to the upper end of the engine. So far with two tows, parts, and labor we are at $2,300. Not close to the opinion of replacing the entire engine at $8,500. No problem with down time as it is a mostly summer driven RV.

[rgatijnet1]

Since you have to do 90% of the work to replace one rod bearing, I would go ahead and turn the crank and do all bearings at the same time. The labor will not be that much more and the cost to redo all of the bearings may be worth it in peace of mind. Of course it is easy for me to spend your money.

[trop-a-cal]

Never run without oil, never over heated and worm gear only worn on one side. That being the case, perhaps shaft of distributor is bent or it was loose and held down of center. Remember the noise started after the fill up and two cylinders full of coolant, dogging the 3 & 5 and perhaps spinning the 7 by uneven downward pressure on crank. Even after the distributor was worn it worked fine at even RPMs and coolant being ingested slightly for 1000 miles tick became knock only after that. So the bearing spin may not be anything to do with distributor filings. Remember the "knock" is not heard over an idle so it's not like there is much movement, as if so it would be louder upon increase in RPMs and a double knock, one up one down.

[JimM68]

I'm with Gary. In frame or not, ALL the bearings must be inspected, as well as the crank itself. This includes the mains.

If a bearing has actually spun, that is major damage.

[C-Leigh_Racing]

PaulJ2 wrote:
And why would there be metal fragments all through the engine? Is not this the oil filters job? Oil pump screen will catch the big chunks and the oil filter should get the rest. I'm with the OP that he maybe has a rod bearing failure, not likely the whole engine.

Well, can never tell, he might have been using a Fram filter.
Neil

[PaulJ2]

And why would there be metal fragments all through the engine? Is not this the oil filters job? Oil pump screen will catch the big chunks and the oil filter should get the rest. I'm with the OP that he maybe has a rod bearing failure, not likely the whole engine.

[FunTwoDrv]

This is not good news… If I understand correctly the current thinking is the engine has a “spun” #7 rod bearing possibly due to distributor gear fragments. That being the case, collateral damage could spread. Here’s my thinking. If the distributor gear did come apart, fragments would have then dropped into the oil pan. Those pieces may still be in there however, the smaller ones could have easily been picked up by the pump and are now anywhere in the oil passages.
Based on the symptoms mentioned, I really think this engine has been run low on (or out of) oil. The usual cause of a spun bearing is loss of oil pressure. The distributor gear failure could also be attributed to this. The oil flow through that engine leaves #7 and 8 rod bearings at the end of the train. In other words, they typically see lower oil pressure and volume as they are last to be lubricated. So, I would be very worried about this engine “ingesting” other parts. Since the tech has to buy a complete set of rod bearings anyway, I would at least check all the others and replace as necessary. I would also have him mic the journals as they could very easily be out of spec now and simply sticking bearings in could easily result in another spun bearing down the road.

Good Luck,
Gary

[trop-a-cal]

Price quote is for new long block engine not rebuilt.

[Daveinet]

trop-a-cal wrote:
Yes, crate is $4,800 plus labor. New 36K or three year warranty...

Quote is higher than retail.

http://www.crateenginedepot.com/74-Ltr-454-CID-GM-ENGINE-1996-2000-New-19207552-P17672C720.aspx

$3839.13 for a brand new engine. That would be a grand off the price you are being quoted or the same engine.

Alternatively GM factory reman is 3200 bucks,

[trop-a-cal]

Advise is from former GM Factory service advisor not shop. As far as the bottom of the rod cap not having a oil opening, I have seen both with and without. This is a Tonawanda 7400 Gen VI L 29.

[trop-a-cal]

The height was checked and nothing was out of spec. That's why the pan was not dropped prior to putting head back on. Turning the crank and replacing bearings can be done, but not indicated yet. The knock is not heard over the engine when above an idle. AS far as cutting losses, so far it's all good, loss would have been to not attempt to repair the engine and rush to a new engine. After all this engine rebuilt is worth close to new engine upon resale. That may be what I do if I go for new crate engine, as core is not required and crate is long block.

[randallb]

s

[st687]

Joe Reath passed on 1-4-2013

[randallb]

A

[trop-a-cal]

The head on the right side only showed low compression and after removal the gasket was leaking between 3 & 5. Head was checked and no cracks as it never overheated.

Yes, crate is $4,800 plus labor. New 36K or three year warranty. GM service advisor says the worm gear worn probably caused the # 7 to get metal in the oil intake of the bottom rod cap and in the bearing area. He also advised not to touch the other rods while pan is off. With 3 & 5 not firing, due to antifreeze in chamber for the half hour after getting fuel, as the valves probably were open and engine hot, may have caused the #7 to do all the work turning the crank in that end position. Possibly spinning the bearing thus the tick, then 1000 miles later the knock as it was out of position. Pure speculation from a subjective analysis which will be confirmed or denied by Objective look see. So if it is fixed the GM man says it's low mileage does not justify the replacement. So it's a gamble, but $3,000 V $8,500 go figure.

As to the oil pump check, yes we will do that, but screen should have got most and it's oil pressure is fine.

[indyzmike]

I agree, remanufactured or crate motor. If you consider what the costs would be if it grenades while traveling, miles from home, a crate motor is not too bad. Towing, motel, labor, and having to find a reputable garage is only part of it. Also, if you replace it now, you can make better decisions because you are not rushed like you would be in an emergency repair. I went through this with our 1990 Pace Arrow with 45,000 miles. Engine blew up 50 miles out of town. At least it was close enough to tow home.