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#3333046 - 04/04/14 07:29 AM 1990 K1500 350TBI Engine Noise Solved
Phishin Offline


Registered: 05/01/12
Posts: 1479
Loc: Indiana
I've made a few post the past few years about my old worn out and tired truck.

It has a neglected motor that was in really poor shape when I got the truck. I removed valve covers and valve train was caked in crud. PCV port in throttle body was plugged. She burns oil really fast. Rough idle. All kinds of "ticking" and "knocking" going on all the time....under acceleration, hot idle, cold starts, etc.

After changing plugs and wires, the engine ran much better (plugs were fouled). I built the throttle body and that helped too. Adding RESTORE to oil and keeping her on a diet of MMO has really cleaned up the engine and I gained further improvement in way the engine runs. So....overall, things were getting better. Issues unresolved: Oil consumption in cylinder #1 is horrific....and the ticking/knocking hasn't improved. In fact, recently, it got MUCH worse.

I could get the engine noise to change when I shifted from park to drive, or drive to neutral, etc. now that the noise was almost deafening. So I had an idea it was the flexplate in the tranny. I got the truck back from the shop last night (flexplate replaced with a new one)....and BOY, this truck is WHISPER quiet!!! It sounds soooo good.

I guess I never had a valve train or bearing problem....piston slap or bent rod. It has always been the flex plate. This morning she fired up from a cold start and it was like BUTTER. I'm a happy camper.

Just posting this in case anyone else thinks they might have a lifter tick or valve train problems....bearing knock or anything else. It was my flexplate.


Edited by Phishin (04/04/14 07:31 AM)
_________________________
2010 Accord-LX K24: PU 5w30
2009 Subaru Forester 2.5X: M1 5w40 TDT
1990 Chevy K1500 350TBI: Frankenbrew
2008 Ruckus 50ccGET: M1R Mix

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#3333056 - 04/04/14 07:43 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
Klutch9 Offline


Registered: 01/07/09
Posts: 1813
Loc: Rochester, MI, US, World
Good job! That is one of the things I miss about owning an older vehicle. There are almost always things you can do to make a noticeable improvement in one area or another, and it feels good. Can be time consuming for sure, but very rewarding.
_________________________
11 Fusion 2.5 - 42K mi - Napa Syn 0w20, RL D6
08 Sedona 3.8 - 72K mi - TGMO 0w20, Amsoil ATF
99 Miata 5MT 1.8 - 123K mi - M1 5w30, RL MT90, RL 75w90

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#3333066 - 04/04/14 07:55 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
novadude Offline


Registered: 01/16/03
Posts: 1350
Loc: mechanicsburg, PA
Many years ago (20-25 years), we scored a '69 396 from an Impala cheap because the owner was convinced that it had spun a bearing. Upon teardown, the crank and bearings showed nothing more than normal wear. Yup.... cracked flexplate.

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#3333081 - 04/04/14 08:12 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
Miller88 Offline


Registered: 04/09/08
Posts: 6750
Loc: Onondaga County
It's pretty common to find XJ Cherokees on craigslist for cheap because they have "blown engine" ... and it's a cracked flexplate.
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'11 Focus PYB 45K
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#3333103 - 04/04/14 08:35 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
eljefino Offline


Registered: 06/15/03
Posts: 24132
Loc: ME
Wasn't this one of Toolhead Gear's problems in his Jimmy 4.3?

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#3333106 - 04/04/14 08:37 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: eljefino]
Miller88 Offline


Registered: 04/09/08
Posts: 6750
Loc: Onondaga County
Originally Posted By: eljefino
Wasn't this one of Toolhead Gear's problems in his Jimmy 4.3?


I may have been. He said it was a conrod hitting the oil pan.
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#3333116 - 04/04/14 08:57 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
jeepman3071 Online   content


Registered: 04/15/10
Posts: 1744
Loc: Storrs, Connecticut
Congrats on finding the issue! I bet it runs awesome now. If most of your oil consumption is from cylinder #1 you may have a stuck or broken ring in that cylinder.
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2000 Jeep Cherokee Sport 4.0L (147k) - PYB 10w30, Napa Silver 31085, Magnefine trans filter

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#3333122 - 04/04/14 09:10 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: jeepman3071]
Phishin Offline


Registered: 05/01/12
Posts: 1479
Loc: Indiana
Originally Posted By: jeepman3071
Congrats on finding the issue! I bet it runs awesome now. If most of your oil consumption is from cylinder #1 you may have a stuck or broken ring in that cylinder.


Yeah. What I was thinking. Its also why I haven't changed valve seals. Usually just one cylinder doesn't need fixed.... Right?

I've done a dozen piston soaks in that cylinder as well. Nothing has worked. From Kreen, MMO, Regane, kerosene.... Even mineral spirits.


Edited by Phishin (04/04/14 09:10 AM)
_________________________
2010 Accord-LX K24: PU 5w30
2009 Subaru Forester 2.5X: M1 5w40 TDT
1990 Chevy K1500 350TBI: Frankenbrew
2008 Ruckus 50ccGET: M1R Mix

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#3333181 - 04/04/14 10:42 AM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
Donald Offline


Registered: 03/21/04
Posts: 13513
Loc: Upstate NY
When people feel its a gunked up or broken oil control ring, does anyone ever pull the head then the piston and clean or replace the ring9s).

Given that the oil control ring could be gunked up or broken and the compression rings fine, its hard to tell the issue.

No flush or soak will cure a broken ring.
_________________________
2001 Jeep Grand Cherokee Laredo 4.0 - PP & M1
1999 Dodge Ram 2500 w/Cummins - Rotella T6 & M1
Amsoil ATF in both vehicles & Magnefine filter.

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#3333294 - 04/04/14 01:21 PM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Donald]
Phishin Offline


Registered: 05/01/12
Posts: 1479
Loc: Indiana
Originally Posted By: Donald
When people feel its a gunked up or broken oil control ring, does anyone ever pull the head then the piston and clean or replace the ring9s).

Given that the oil control ring could be gunked up or broken and the compression rings fine, its hard to tell the issue.

No flush or soak will cure a broken ring.


Well Donald....the old 350 has 185k miles on her. Now that I know she might be in better shape than I thought, it's a possibility to pull the head. Problem is: I don't have the tools to do it (that's never stopped me). I've never done it before (that's never stopped me though either). If I had enough spare time to do it, maybe I'll attempt it.

But right now, I have 120 quart of Maxlife that I got for $1 each, so burning oil isn't hurting me too bad. Plus, the old 350TBI is a breeze to shoot a gallon or two of water down the intake to give her internals a good steam cleaning.

The real question is: Is it likely that the engine will only last another 10-20k miles burning a bunch of oil in one cylinder but would last another 100k miles if it's fixed?
_________________________
2010 Accord-LX K24: PU 5w30
2009 Subaru Forester 2.5X: M1 5w40 TDT
1990 Chevy K1500 350TBI: Frankenbrew
2008 Ruckus 50ccGET: M1R Mix

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#3333429 - 04/04/14 03:52 PM Re: 1990 K1500 350TBI Engine Noise Solved [Re: Phishin]
Donald Offline


Registered: 03/21/04
Posts: 13513
Loc: Upstate NY
Originally Posted By: Phishin
Originally Posted By: Donald
When people feel its a gunked up or broken oil control ring, does anyone ever pull the head then the piston and clean or replace the ring9s).

Given that the oil control ring could be gunked up or broken and the compression rings fine, its hard to tell the issue.

No flush or soak will cure a broken ring.


Well Donald....the old 350 has 185k miles on her. Now that I know she might be in better shape than I thought, it's a possibility to pull the head. Problem is: I don't have the tools to do it (that's never stopped me). I've never done it before (that's never stopped me though either). If I had enough spare time to do it, maybe I'll attempt it.

But right now, I have 120 quart of Maxlife that I got for $1 each, so burning oil isn't hurting me too bad. Plus, the old 350TBI is a breeze to shoot a gallon or two of water down the intake to give her internals a good steam cleaning.

The real question is: Is it likely that the engine will only last another 10-20k miles burning a bunch of oil in one cylinder but would last another 100k miles if it's fixed?


What is the compression in the one cylinder that burns oil?

So there is something out of whack in that one cylinder. If its an oil control ring issue it would seem its broken since one would think all 8 would be cruded up in a similar manner. The other thing or in addition is a bearing can be bad and squirting more oil onto the cylinder wall than even a new oil control ring can scrape off. It does squirt some and thats needed, just cannot squirt too much.

This is a workhorse engine. You probably have 4 bolt mains since its in a truck. I had one in my 1993 Suburban (sold) and also have one in my boat powering a Mercruiser. There must be a zillion of these 350 engines in Mercruiser powered boats.
_________________________
2001 Jeep Grand Cherokee Laredo 4.0 - PP & M1
1999 Dodge Ram 2500 w/Cummins - Rotella T6 & M1
Amsoil ATF in both vehicles & Magnefine filter.

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