Chain Guide Failure

new 9/5/04

Larry , here is the copy of my chain guide failure log .

1: The first sign of problems was the low oil pressure light and SES coming on periodically .

2: Shortly after a slight knock began to develop that sounded as if it was coming from the engine block its self .

3: The oil pressure finally dropped low enough to keep the oil light on and it was time to pull the pan and inspect the problem .

4: Pulling the pan was fairly easy and the only obstacle was the cats that just needed to drop a few inches in the front . After draining the pan I found very thick crud and small shavings of steel . I feared the worst at this point thinking bearing failure .

5: After pulling the pan I found thick sludge that was kind of like wet sand that was built up in the bottom of the pan and actually was thick enough to plug the pickup tube/screen not allowing oil to prime the oil pump . I did not recognize this and thought to myself that this engine was just badly neglected and never had an oil change in the 104,000 miles of its life .

6: I visually checked all of the rod and main caps/bearings for excessive damage and found no damage at all . All of the piston pins looked snug when I turned the engine back and forth so I elected to install a new pick/up tube and hope that the knock was just lack of oil to the engine and the very minute shavings where minor damage that may have occurred over time and be ok . Never assume this !!!

7: I reassembled the oil pan using black gasket maker and reassembled the cats to their proper place .

8 : I removed the sending unit just above the oil filter and plugged in a pressure gauge . Filled the new oil filter w/5 w 30 installed it and filled the engine w/6 quarts of oil .

9 : I started the car and the oil pressure shot up to 48 lbs as it should and the knock slowly faded away . I was one happy camper at this point thinking all was well . NOT SO !!!

10: Oil pressure was fine until I drove it to full temperature level and the light started to flicker again . The knock started to come back and I was pissed . The bearings where good and the pump was good so what could cause this ???? 11: I went out the next morning and went to start the car and it locked up as tight as a frogs ass . I thought for sure it had thrown a rod.

12: I pulled the engine and this is what I found after pulling the timing cover .

12a : The chain guide that the timing chain rides on had broken completely off and the debris/chunks from the broken guide had lodged themselves between the chain and gear in the center of the engine causing it to lock up .

12b: It turned out that the wet sand like sludge in the bottom of the oil pan earlier was the neoprene materials from the guide that had worn down .

12c: The knock was the chain slapping against the worn down guide .

12d: The chain had beat the guide hard enough to break it completely in 1/2 .

12e: It took off 5 of the gears on the center gear .

12f : After pulling the heads, 4 of the exhaust valves had collided w/the pistons causing them to bend like a cam failure would although it was not cam failure .

12g: The neoprene had worked its way throughout the engine causing the whole engine to sludge up from the mixture of plastics and hot oil .

12h: The cam journals wore excessively and the heads are shot as well as 3 of the cams because the sludge had stopped oil from getting to the vital areas . The sprockets where fine .

12i: Every oil port was clogged . This engine was a cheese toasty !

13: The summary: The first sign will be the key to saving an engine . If you have low oil pressure take the time to pull the pan . If you see the sand like sludge , take no chances and bet that it is material from the chain guide . Pull the timing cover and inspect the guides . Once this plastic like material mixes w/the oil and circulates throughout the engine, definitely count on flushing it out several times to clear all of the ports . Pull the valve covers and clean the deposits left from this caked on baked on sludge . Check the cam journals for wear due to lack of oil penetration . If you catch it quick enough , you may get luckier than I did . If I could have caught this quick enough the engine would still be in the car . After it locks up it is likely done for w/hidden bent valves !!!! Never take the flashing oil light lightly . It may be catastrophic . Also while you're in there "Weld the cams and do the extras" (see cam welding)

I hope that this saves a few more SHOs from certain doom !

One final thought . I did end up having a good block in the end and the trashed heads make nice jigs for welding loose cams. Expensive jigs they are though and the block will need rebuilt .

B.King 13

Some folks prefer a quality synthetic motor oil with frequent oil changes. Other folks prefer Very frequent oil changes with a quality dino juice. Either way a SHO motor is no place to "save money" on oil changes.

Thanks for sharing,

Buford

BTW, Brian did not neglect this car, he purchased it that way.