Jump to content
CaddyInfo Cadillac Forum

Engine knock?


danbuc

Recommended Posts

Well, I've had this knock for a while now, and I finally got around to pulling the intake cover, and looking for it. I got out my trusty have inch, 2 foot section of rubber fuel tubing, and went to town. I checked all around the edge of the intake manifold, I checked on the side of the block, above the crank pulley, I checked verywhere I could. When I slipped thew hose underneath the manifold, up against the top f the block, that's when things got interesting. With the hose pressed up againts the top of the block, near cylinder #1, the noise was loudest and clearest.

Looing in my Service manual under Engine Noise Diagnosis, they list a few different types of knocks.

A main bearing knock happens at every engine rotation. Since this knock barely increases it's rithym, whether at 600rpm, or 1500rpm, I've decided it's not that.

A connecting rod bearing knock will increase volume with engine speed, and is loudest unde decceleration. Since this knock does not get louder when the engine rev's, I've also determined that this is not the source.

The one that really interests me though, is a timimg chain, or sprocket noise. They say it's the most common type of abnormal engine noise, and usually in the form of a high frequency knock. My engine knock, is relatively high in pitch, and seems to be located high up on the engine. It then says that this noise will generally be the same intensity, whether at idle, higher speeds, or under load. Since the knock does not change volume when you rev the engine, and end up get drowned out by other normal engines noises, I believe I might have finally found the source.

I'm going to remove the valve covers at school next wekk if I can, and inspect the cam gears for worn, or broken teeth.After that, I'll need a way to pull the front cover, and inspect the intermediate sprocket, where the timing chain attach. That's going to be a pain.

Sorry for the random post, I just had tell you this. It's been bugging me for almost a year, and now I think I've finally solved it. All I need to do now is fix it...hehe. :lol:

Link to comment
Share on other sites


This is not a random post. Its great. I am very interested in how hard it is to take your valve covers off...you might want to purchase new valve cover gaskets and or seals for when you reinstall them. Isn't there a chain tensioner in there? Good Luck, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

Link to comment
Share on other sites

Yeah, I'm going to buy all new gaskets when I do it. To remove the front cover, I have to pull the crank balancer, remove the accessory pulleys that are in the way, remove the front cover oil seal, pull out all the bolts, and then it should just come right off. This will then expose the end of the crank, and the intermediate sprocket, and timimg chains. I can also access the chain tensioners from here too. This is going to be a crap load of work, but I'm definitely going to do it myself. I'm not sure how exactly, but I'll get it done. If the chains, sprockets, and tensioners are all bad, I'm just going to replace every thing. Oh boy, I can;t wait to get started. <_< . Now all I have to do, is find a place where I can pull the engine, and work on it.

Link to comment
Share on other sites

Thanks, but at this point I think the Schwartz may be of more help to me now...hehe. The one thing I do know, is that it's going to be fun, and crappy all at the same time. I have a lot of work to do, beside that also. I have to get new rotors, since the front ones have been burned really bad (brown rings around rotors with strees cracks :( ). I don't know how it happened, but it's pretty bad. I also need some new mounts, and an ignition module and coil pack. All I need now, is to win the lottery, and own my own garage and I'll be set. :lol:s

Edited by danbuc
Link to comment
Share on other sites

If you get a chance take some photos, Mike

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

Link to comment
Share on other sites

The one thing I do know, is that it's going to be fun, and crappy all at the same time.

All I need now, is to win the lottery, and own my own garage and I'll be set. :lol:s

Yeah, I know the feeling there danbuc. A major project is exciting, but you know in advance there will be some setbacks and grunge moments! :P

Yes, having your own garage is a huge advantage of course. I have a three-car, but with six vehicles at our place the garage is in high demand! I bought a new motor on Ebay a week ago to drop in my daughter's 96 GrandPrix, but I don't want to plug up the garage for too long when the weather is crappy like this. (10" of snow in the last 2 days) I look at that new engine sitting there on that skid and it is calling me though! B)

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

Link to comment
Share on other sites

Being at school, and in another state too, just makes it worse. I just don't have any time. Seeing as how it's running perfect (besides that knock that is), I'll probably hold off on it for as long as I can stand the noise. I'll just do the brakes, ignition module, and mounts first.

thexboxpiii, it doesn't sound like a diesel really, more like knocking on a wooden door or table, with a much higher pitch. Hmmm...that doesn't really make much sense, but it's the only way I can describe it. It's not really loud like a diesel, and it gets drowned out, when you rev the engine.

If I can, I'll try at get a sound recording of it next weekend if I get a chance.

Scotty, when I end up doing the work, I'll definitely take a bunch of photos. I'm thinking I might do it this summer, since I'm hoping to use my Mustang as my daily driver this summer at school. That will give me some extra time, to work on the car back home on the weekends.

Link to comment
Share on other sites

"... I'll need a way to pull the front cover, and inspect the intermediate sprocket, where the timing chain attach.  That's going to be a pain."....

I would be surprised if anything was wrong with the timing chains and sprockets, they are extremely durable.

On the off chance that you have a stuck/sticky lifter, you could try running one quart of Marvel Mystery Oil to try and free it up. Marvel will not hurt your engine and has proven many times to be helpful in freeing sticky lifter and rings. It won’t fix broken parts of course, but it can work its way into areas stuck or clogged with varnish.

Should you decide to remove the front cover, it is vital when replacing the vibration dampener to torque it down properly + the added degrees of rotation. The oil pump is dependant on the vibration dampener “pinching” the inner rotor in place. If you do not do this in the correct manner, your oil pump will not work.

If you decide to remove the timing chains for any reason, it is best to have the engine at #1 TDC with ALL of the timing marks lined up. The timing marks will only align once in eight revolutions. Do not rotate the engine or cams with the timing chains removed; the valves are very easily bent by piston interference due to their small sizes.

-George

Edited by growe3

Drive'em like you own 'em. - ....................04 DTS............................

DTS_Signature.jpg

Link to comment
Share on other sites

Thanks for the suppoirt Growe3, but the knock is definitely coming from withing the block itself. There is no way a stuck lifter is going to cuase a knock like this. Maybe a loud tapping, but definitely not a knock.

I've got the factory service manual, so I'll know what the toprque proceedure is, when I ever get around to it. I'm going to have some of my teachers check out the noise on monday also, but I'm pretty certain that it's comimg from something to do with the timing chain. All the symptoms match what it says in the manual. The noise is even the loudest, where the intermesiate shaft is. I have a pretty good feeling that where I'l find the problem, if I ever have the time to mess with it. I'll also try taking it to the dealer and see what they have to say, but the last couple of times I tried that, none of them had any clue what could be causing it.

Link to comment
Share on other sites

Hi Danbuc,

Good luck on your inspections.

I don't know if you have seen a couple of Northstar cutaways, but they may help you get an idea of what is in the front cover. I still don't know what could produce a knock in this area.

If the bolt that holds the intermediate sprocket in place failed or got loose somehow, I suppose that the sprocket could flop a bit, hard to belive that that could happen, unless someone had been in the cover at some point and did not put the bolts back in correctly.

Another possibility would be a chain tensioner that failed or got loose.

I would be very interested in what you may find that is causing the knock.

I can only attach one image, at a time so look for another image in the next reply.

-George

post-3-1111359674_thumb.jpg

Drive'em like you own 'em. - ....................04 DTS............................

DTS_Signature.jpg

Link to comment
Share on other sites

Very NICE cutaway! Love it

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

Link to comment
Share on other sites

Here is the second image.

-George

post-3-1111360170_thumb.jpg

Drive'em like you own 'em. - ....................04 DTS............................

DTS_Signature.jpg

Link to comment
Share on other sites

I think that a tensioner could be going, a maybe one of the sprockets has a chipped tooth, causeing the chain to hit the tensioner. I guess I'll find out, when I get around to pullin ghtat cover to take a look. In the meantime, I've got my hands full, with replaceing the engine and trans mounts, the brakes, and the ingition moduale, and coil packs. Because if the lake of time, I think I might use the aluminum mount from RSM. They are alot stronger it seems, and they are also smaller in size. The smaller size is more of a deciding factor for me, since I need to slip in it between the frame, and I'll need all the space I can get.

Link to comment
Share on other sites

This is not a random post. Its great. I am very interested in how hard it is to take your valve covers off...you might want to purchase new valve cover gaskets and or seals for when you reinstall them. Isn't there a chain tensioner in there? Good Luck, Mike

I understand that the REAR valve cover is hard to get off. I am thinking that I need to change the seals/gaskets on my valve covers, so I am curious how hard you find getting them off. Thanks

Early on sailors navigated by the stars at night and the North star became the symbol for finding ones way home. Once you know where the Northstar is you can point your ship in the right direction to get home. So the star became a symbol for finding ones way home or more symbolically even finding ones path in life.

Link to comment
Share on other sites

I am surprised that no one has suggested this is just carbon build up that is causing the knock. This has been mentioned several times in the forum's previous life, you might do a search on this forum first.

Anyway, there is very little clearance between the flat part of the piston and the cylinder head and slow driving may well build up enough carbon to cause this knock. The cure is some rather hard driving, starting out with some medium throttle operation and working up to wide open throttle say, up a mountain pass, or at least a very long hill.

Jim in Phoenix

Link to comment
Share on other sites

I've had the top engine clean done (was a total waste of money), and I routinely give the car a good WOT, to clear out all the carbon. It doesn't sound like the piston is hitting any carbon build up, inside the combustion chamber. Since I don't ahve alot of time right now for something this complicated, I think I'm just going to do the brakes and other stuff.

By that way, that reminds me. Since I need new brakes and pads, I was wondering if anyone had any input as to what would be best. I'm basically just looking to see what people are using, and how well it has worked for them. I was thinkg about the AC Delco Durastop rotors, and either the durastop pads, or maybe Bendix or Raybestos or something. I'll probably end up getting ceramic pads, just not sure which company.

Link to comment
Share on other sites

My money is on a stuck chain tesioner. I remember from a year or two ago, that Guru said that the tensioners are actuated by oil pressure. In other words, oil pressure forces them out against the chains, but a ratcheting mechanism keeps the out there until the next startup. Anyway, this is a low oil flow area, due to the nature of the design, and a stuck tesioner can happen. Unfortunately, being a low flow area, the chances of Marvel Mystery Oil, or any other solvent freeing it up are slim to none.

As to the brakes, unless you drive the car really hard, like racing hard, I'd be looking for some stuck calipers. Brown stains and heat stress cracks do not develop normally under normal driving conditions. Well, sometimes brown stains do, but not on the rotors.

Last, I've installed to Bendix Titanium pads on the front of my '99 STS. All the parts and connectors were included for about $50.00 less than the dealer supplied Delco parts. To date, about 6 months of use has shown them to be superior in cleanliness and stopping ability (no brake dust). Nothing but good things to report about them at this time. Longevity could be an issue...I'll let you know after I put about 50,000 miles on them!

Never underestimate the amount of a persons greed.

Link to comment
Share on other sites

The rotors originally cam ewith an anodized black finish on them. I think in the process of wearing that down to the metal, some of it stayed won the pads. That might explain why only certain parts of the rotors seem damaged from heat, as if patches of material had stuck to the pad. It's seems like where the material was on the pad, heated that particular section of the rotors, to the point of tunr in brown and forming stress cracks, while the other areas, seem completely untouched. Overall, I think it's prabably the worst design flaw I've ever seen. Having to wear away that surface to reach metal, obviously didn't work out as they has planned. Some of it got stuck on the pads.

Like I said, I don't race the car, and I don't drive it extremely hard. In fact, lately, I've tried to drive it as carefully as possible, to help extend what ever life was left in these pads and rotors. It seemed it didn't help though. <_<

Link to comment
Share on other sites

Well, it sounds like you are pretty level headed and open to the fact that what you have heard for all these years may actually have NO basis in fact whatsoever. There are people that believe there is NO SUCH THING as a warped rotor, and some of what you say in your post sounds like you have actually figured that out for yourself! That's pretty amazing to me...very perceptive. Here is a link that might confirm what you suspect and help you get the brake performance that you are looking for.

http://www.stoptech.com/

As for me, I'll stay with the Bendix Titanium, for my money it's a good choice. You, on the other hand, need to find some rotors. Stay away from the Chinese junk, too thin to absorb the heat and can only be refinished once.

Never underestimate the amount of a persons greed.

Link to comment
Share on other sites

Well, I looked up that StopTech website, and downloaded their pdf application guide and price list, but they didn't have anything that fit my car.

I think I'll probably go with the AC Delco Durastop rotors, and those bendix pads. That seems like a pretty good combo to me.

Link to comment
Share on other sites

Actually, the point of my post was NOT to sell you pads or rotors from this site. I know that may be hard to understand in this day and age. However, if you click on the "Technical" tab, you may learn a little more about your problem and figure out a way to avoid a recurrence.

Never underestimate the amount of a persons greed.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...