deezel Posted December 14, 2004 Report Share Posted December 14, 2004 Ok, I know BenKey and a few others have had issues with cam bearings. I looked back at Ben's thread and am wondering if my engine is heading in that direction. Here's what I am noticing: 1) So far, I have not noticed any loss of oil pressure. Sits about 38-40psi idle and ramps up to around 70-80psi on high rpm runs. I have never run the motor without oil pressure other than the 1-2 seconds it takes after an oil change to repressurize the system. 2) I have never revved the engine above 6000. Perhaps 10-15 times up to 5900 on the 1-2 shift. My normal shifts are set at 5600-5800 for all of my tunes. 3) My main concern is an intermittent squealing, binding noise coming from, I believe, the front of the engine. The first few times I heard it when driving, I thought it was the belt slipping - mainly because it will sometimes happen when I romp the gas and then let out after a shift. So, it seemed like it was just a "rapid rpm change" induced squeal - ala belt slip. But, more recently the noise has been happening on normal medium-heavy acceleration (not WOT, not just around shifts). It doesn't happen all the time... comes and goes randomly. I'll think the engine is sounding fine again, then screech, it happens again. Sometimes the sound is very slight, almost like a louder version of the normal alternator whine. Rarely, it can sound loud like a squealing belt. I have a new gatorback belt on there which is pretty snug, so I'm sure its not that. 4) Changed the plugs recently and all 8 have similar appearance - no red flags there. Changed the oil recently and looked for metal shavings, etc. Nothing significant, just a tiny, normal amount of "dust" on the drain plug magnet - no sparklies in the oil or filter. 5) I have been taking it easy on the motor lately, but I'm wondering how concerned I should be. I have considered trying to get the dealer to investigate this, but am worried about the competency of the service departments around here. If it is a cam bearing, how long would it take them to figure it out? I'm guessing they would say they can't reproduce the noise. Naturally I would return the engine to as near stock as possible. Easy enough to remove the n2o kit, plugs, wires, intake, e-fans. Oil change and stock plugs would be in order. I would return the PCM flash closer to stock (except !cats). Not sure if putting the t-stat back would be worth it. The things I cannot reverse are the P/P throttle body, cleaned cats, shift kit, and descreened MAF (the screen is no longer in "perfect" condition - it would probably be noticable, but I could give it a try). 6) Of course I would be interested in a cam swap if this is the issue. However, I am not familiar with replacing the cam bearings. How much is involved with putting new bearings in? Are we talking engine removal, or top end disassembly? Thanks for any help or advice you guys can offer. I hope I'm being over cautious. So, having said all this, how concerned should I be? Link to comment Share on other sites More sharing options...
ChevySSandChevy8.1 Posted December 14, 2004 Report Share Posted December 14, 2004 From what i remember about spun cam bearing. the bearings are crescent shaped and they snap into place forming a complete circle when the cam is completely bolted together. The rod bearing is half of the circle which is on the rod and other half goies on the rod cap. When oil pressure gets too low, the barrier it forms breaks down and you get more friction between the bearing and the crank journal that the two halves wrap around. The journal will "grab" the bearing and start spinning it around in there. It'll eventually wear enough material away that you get knock and possibly a window in your engine block. Make sure your oil level is full all the time. There might be a slight tinkling noise. II am not sure what the problem with your motor is but i don't think its a spun cam bearing. Maybe having the dealer investigate is not a bad idea. Do any engine lights come on? Then you could get it read. Hope this was helpful and good luck Link to comment Share on other sites More sharing options...
TurbochargedBerserker Posted December 14, 2004 Report Share Posted December 14, 2004 On a similar note, Ben recommended that I replace the cam bearings as I rebuild the motor and I think that is good advice. I believe Ben has a specially coated set of bearings? Link to comment Share on other sites More sharing options...
BenKey Posted December 14, 2004 Report Share Posted December 14, 2004 If the cam bearings are going, your oil pressure will start to fade. From what you have said, I would guess that you're okay. My oil pressure was good at start-up and as the engine warmed up and the oil thinned out, pressure would nearly bottom out while at idle. This is when you learn we have a low oil pressure warning that will go off I would monitor it to be sure and notice what you have now to compare to it later. I'm sure you're doing that. The cam bearings are pressed into the engine by a special machine, and from what I understand, it can only be done with the engine out, heads off. The cam bearings are one piece, the main bearings are crescent shaped. What starts to happens is the clearances that you have in the journals start getting too big and you get blow-by. Once they start getting really damaged from driving it like that, they can potentially reach a point where they will actually stick to the cam from the intense heat. Two of mine did this, anyway. Have you possibly inspected your motor mounts? If loose at all, I could see where they could make noise in a WOT transition phase. Link to comment Share on other sites More sharing options...
deezel Posted December 14, 2004 Author Report Share Posted December 14, 2004 Thanks for the quick replies. I have scanned for DTC codes - none present. I will continue to keep a close eye on the oil pressure. I suspected that the cam bearings were not easy to replace. Hopefully its something less drastic. Could bent pushrods or maybe a bad lifter create an intermittent sound from the motor like I described (whirring, squealing sounds)? I guess I should do a compression check to rule out bent valves or bad rings... Link to comment Share on other sites More sharing options...
styleandspeed Posted December 15, 2004 Report Share Posted December 15, 2004 Seriously sounds like just a belt to me. Look and see, if it isn't cracked, then look for some small shiny deposits inbetween the grooves. Link to comment Share on other sites More sharing options...
CrAzYMoPaRGuY Posted December 15, 2004 Report Share Posted December 15, 2004 Cam bearings are usually hammered into place with a cam bearing installation tool, it is slipped into the cam journal area, the bearing is held in place by the tool, which has a raised edge at the rear that drives the bearing into place. It is tapped into place, with care taken to line up the oil holes in the block with the holes in the bearings. Hence.... If a cam bearing "spins" it will not let the oil holes line up. Depending on where the oil holes were supposed to feed will depend on where the engine will starve for oil. Link to comment Share on other sites More sharing options...
TimC3 Posted December 15, 2004 Report Share Posted December 15, 2004 Been down the "spun cam bearing" yellow brick road before... Same as with BenKey, at idle the oil pressure would plumment to 0 and the Oil pressure light would come on.. Also, there was a very noticeable, loud "knock knock knock" (not just CSK either.. You could really hear this thing bad).. Luckily when it happened to me it was a pretty quick thing.. I noticed it on an offramp, about a 1/2 mile from the parking lot at work, so when I got it parked, I called the Extended Warranty place immediately.. This was all before any of my mods though (except exhaust). Keep us posted on what you find out.. Link to comment Share on other sites More sharing options...
hellbents10 Posted December 15, 2004 Report Share Posted December 15, 2004 Doesn't sound like a bearing to me. does it happen when your compressor kicks on and off? Do you have the AC or defrost on while it happens. Maybe its just something simple like this. Link to comment Share on other sites More sharing options...
56chevywagon Posted December 15, 2004 Report Share Posted December 15, 2004 If it's a squeeling, from the front of the motor, it is most likely either...the belt slipping, the water pump bearings going or gone bad, or the alternator bearings going or gone bad, or the A/C clutch going bad, or any one of your idler pullies. I have never heard of any internals failing and causing a squeeling noise. Like some of the previous post said, a spun cam bearing would give you low oil pressure and a knocking/clattering from the motor. Hope you can find out the prob. Also, if it occurs when your turning, that's a sign of low power steering fluid. Link to comment Share on other sites More sharing options...
CrAzYMoPaRGuY Posted December 15, 2004 Report Share Posted December 15, 2004 However, I am not familiar with replacing the cam bearings. How much is involved with putting new bearings in? Here deezel, this page gives you some idea of how and where cam bearings go. A spun cam bearing is very rare, especially from the factory... Cam bearing installation... Link to comment Share on other sites More sharing options...
deezel Posted December 15, 2004 Author Report Share Posted December 15, 2004 Thanks again for the feedback. No A/C engaged when this happens, normal or defrost/defog mode. I also considered water pump bearings or the main idler pulley. Any way to tell if its the water pump besides replacing it? Link to comment Share on other sites More sharing options...
GUNNER Posted December 15, 2004 Report Share Posted December 15, 2004 Simple way to see if it is any of the accessories on the front of the engine is to run it with no belt when cold. Heat shouldn't be an issue this time of year. You should have planty of time to take a quick trip and that way you will know for sure. This eliminate the compressor, water pump, power steering pump and so on. Link to comment Share on other sites More sharing options...
deezel Posted December 17, 2004 Author Report Share Posted December 17, 2004 Simple way to see if it is any of the accessories on the front of the engine is to run it with no belt when cold. Heat shouldn't be an issue this time of year. You should have planty of time to take a quick trip and that way you will know for sure. This eliminate the compressor, water pump, power steering pump and so on. <{POST_SNAPBACK}> I plan on trying that this weekend. I will report back my findings. I ran it for a minute or two in the driveway with no belt, but its not the same as driving it with the engine under load. Link to comment Share on other sites More sharing options...
n2opwr Posted December 26, 2004 Report Share Posted December 26, 2004 A spun cam bearing will often result in a "chirp, chirp, chirp" sound. The AC belt is a seperate belt, so it is easy to take it off and listen for noises. Link to comment Share on other sites More sharing options...
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