I know I posted before in regards to my 95 sedan deville knocking when I accelerate. I did some of the recomendations off the forum, like cleaning the throttle body I took it off the manifold and cleaned it with throttle body cleaner (CRC) brand. at the same time I replace the EGR valve. replaced some very brittle hoses as well. job took around an hour.

double checked everything to her for a spin, didnt get to the next light when I heard the engine knocking again?? this time the engine is knocking longer from the start into 2 gear of the trans shifting! am I doing something wrong? I have a OBDI I dont have codes?

what should I do now? I would like to have this car running like a cadillac should be running..

any and all positive comments well appreciated

SRTATEU

Sure it's a knock? How's it sound at idle. How hard are you pushing it. Engine sounds a bit different when you're "on" it. Performance up to snuff? Done any WOT's lately. Could be carbon build-up. Oil fresh and not over filled, within the hashes when checked hot. K_C

This is a 4.9. Did you rod out the EGR tubes in the TB?

heh heh, if you have a 4.9l yer in same boat as me then buddy, main bearing thump, you want it to go away? go to your local caddy dealer ship, ask them for the "blue bearing" for the 4.9 #1 position, they are going to try to tell you its discontinued, but i think hammond indiana has one more, they are about 60 bucks i think, its a .032mm Under size bearing made specifically for the #1 position (the one that ALWAYS knocks) drop your exhaust, drop your oil pan, slide the number one out slip the new one in and drive it away knock free.

I forgot about the "main bearing thump", but I believe that is only at idle. You can trouble shoot that very easily. At idle, release belt tension just enough to let the belt slip. If the noise goes away, it's the main bearing. My understanding is that it is nothing more than annoying. 15W40 may help if that is the problem.

This is a 4.9. Did you rod out the EGR tubes in the TB?


Ranger,

thank you and everyone else that replied. I took off the T.B. completely and cleaned it with T.B. cleaners. use a rod to clean all the channels and everything. replaced the old EGR with a new OEM one. also replaced all the brittle rubber hoses. and the knocking got worse? now it does it off the line and even after getting into second gear. I did a wot on 355 from 55 to thorndale thinking I could get rid of some carbon built up that way and nothing?
whats this bearing? how hard is it to change it? I really dont have mechanics exp. if you know what I mean..

help!

Joel

I forgot about the "main bearing thump", but I believe that is only at idle. You can trouble shoot that very easily. At idle, release belt tension just enough to let the belt slip. If the noise goes away, it's the main bearing. My understanding is that it is nothing more than annoying. 15W40 may help if that is the problem.


I dont hear the knocking at idle. I hear it when I am cruising 15-35 miles per. when I step on the gas it goes away but when I am at a cruise speed again it comes back?

Then it is not the main bearing. If it goes away when you step on the throttle, it is not spark know either. Are you sure it is not a belt pulley bearing? Does it do this in neutral? Maybe it is driveline related and not engine related.

Then it is not the main bearing. If it goes away when you step on the throttle, it is not spark know either. Are you sure it is not a belt pulley bearing? Does it do this in neutral? Maybe it is driveline related and not engine related.


I had a mechanic look at it this morning and he put it in gear and held on the brake and stepped on the gas, he stepped on it light and hard at times and he didnt hear the engine knock? he did it in reverse as well and nothing! am I hearing things then? I know I am hearing a knocking I just dont know from were!

how hard is it to change the belt tensioner? do you have a 1-5 easy step to change the tensioner on the forum? lol..

Ranger thank you for all your input A+++ for being the moderator..

Joel

Strateu, when you had the throttle body off did you look down inside the manifold and see if those tubes sticking up needed to be cleaned out? I'm getting the sense that you cleaned the TB only. I can't remember right now but I think you can see them by looking through the TB. I wonder if you are possibly hearing an exhaust leak or something.

Don't change the tensioner unless it's bad. Use a 1/2" drive breaker bar and put the drive lug in the square hole on the backside of the tensioner arm. Use the bar as a lever (engine off) to release the tension. Spin the tensioner and idler pulley by hand. Look for wobble and feel and listen for bearing roughness.

I had a knock in my '97 ETC (different engine, I know) under light throttle, the dealer could not fix it, even replaced the engine, it turned out to be the catalytic converter matrix rattling. They replaced the cat, problem solved.

Hope that helps

Don't change the tensioner unless it's bad. Use a 1/2" drive breaker bar and put the drive lug in the square hole on the backside of the tensioner arm. Use the bar as a lever (engine off) to release the tension. Spin the tensioner and idler pulley by hand. Look for wobble and feel and listen for bearing roughness.

Ranger, I read your message a little to late I went and bought the tensioner this morning at NAPA, took it to my local mechanic he replaced it in 10 minutes and the same thing!!! engine knock off the line... WTF... So I made an appointment with Hertiage cadillac in lombard at 8am. to see if they could figure out the knocking problem!

Cadillac Al, thank you for your response When I bought the car I immediately made the deville dual exhaust not true exhaust but looks bad ass!! and the converter was still solid, pics to follow. and really cheap too! under $150

I will post with the day in a life of the unknown knocking tomorrow after I get it back...

thank you all again for your time and wisdom...

SRTATEU

ive got main bearing thunp on my 4.9, and once the oil gets warm i hear it at idle in gear, and all the way up be it heavy acceleration to light cruising.

I would suggest a close look at the exhaust work you did on it. Cat rattle can be hard to trace, hanger connections, and clearances all change under driving conditions. Knocks want to be heard, rattles are usually what you hear. Not sounding engine related to me. K_C

I would suggest a close look at the exhaust work you did on it. Cat rattle can be hard to trace, hanger connections, and clearances all change under driving conditions. Knocks want to be heard, rattles are usually what you hear. Not sounding engine related to me. K_C

K.C.

I will also have that looked at as well! I really hope its something that can be a simple fix..

thanks again

Joel

Mine did that till I replaced the muffler bearing, well actually it was the donut gasket in between the
exhaust manifold and the exhaust pipe.

Mine did that till I replaced the muffler bearing, well actually it was the donut gasket in between the
exhaust manifold and the exhaust pipe.

Don won,

I am taking it back to the muffler shop as we speak! Yes I am proud owner of a PDA. I will have them check it from front to back to make sure that its not leaking..

thank you

SRTATEU

ive got main bearing thunp on my 4.9, and once the oil gets warm i hear it at idle in gear, and all the way up be it heavy acceleration to light cruising.

Lithorian,

I received your pm. I have to have 30 posts b4 I can use this feature? who made this up?

I need 3 more lol...

SRTATEU

Keep posting! K_C

Keep posting! K_C


I need 2 post pips! help me out!!!

SRTATEU

Don't change the tensioner unless it's bad. Use a 1/2" drive breaker bar and put the drive lug in the square hole on the backside of the tensioner arm. Use the bar as a lever (engine off) to release the tension. Spin the tensioner and idler pulley by hand. Look for wobble and feel and listen for bearing roughness.


Ranger and friends, The problem of the engine knocking has been solved!!! whoo hoo!!

thank you all for your comments and support!!

SRTATEU

:highfive:Don't change the tensioner unless it's bad. Use a 1/2" drive breaker bar and put the drive lug in the square hole on the backside of the tensioner arm. Use the bar as a lever (engine off) to release the tension. Spin the tensioner and idler pulley by hand. Look for wobble and feel and listen for bearing roughness.


Ranger and friends, The problem of the engine knocking has been solved!!! whoo hoo!!

thank you all for your comments and support!!

SRTATEU

:highfive:

So what was the problem?

yea i want to know too lol

I want to know too, also.

And the answer is....................? K_C

So what was the problem?

yea i want to know too lol

I want to know too, also.

And the answer is....................? K_C

well the dealer did a vaccum test and found more broken hoses than I did. when I took off the T.B. over the weekend I thought I replaced all the brittle hoses that connect to and around the T.B. now the 4.9 is burring like a
p---y cat Boys! After I changed the EGR, Belt tensioner, and I thought all the old brittle hoses. It was worth it though and least I know now that I have a strong running 4.9!!

I want to thank each and everyone of you all for your input...

SRTATE