Engine knock

I need a bit of help here guys. Maybe you guys could give a bit of help. I have a 91 Caprice wagon with a 305. It has a like a timing knock when it is heats up and I accelerate. It had the check engine light come on and had an EGR code so I changed the EGR Valve and the EGR solenoid and it still has the knock. I know the catalytic converter was going bad so I had the catalytic converter changed for a new one, and the damn thing still has the knock. I was told to try a can of Seafoam in the gas tank hoping it help and nothing. I do not know what else it could be. Could anyone give me some sort of help this knock is driving me up the wall? Before this started I did have the intake gasket redone and it has been like that since.

Sounds like you need to put a timing light on and and verify engine timing. If you did the intake gasket, you need to re-set your timing.

Make sure you unplug the ESC (electronic spark advance control) plug on the passenger side of the intake manifold. Set your base timing, then plug it back in. Don't set base timing with the plug connected or you'll be off, and get what you describe possibly.

Before setting the timing, check the location of the timing mark against the location of the piston.

If the harmonic balancer has spun the timing mark will be in the wrong spot. It is also possible that the balancer can rock back and forth, which will sound very much like a front crankshaft bearing knock, and is more likely to occur when the engine is warmed up.

If the timing mark is in the correct place, then proceed as above. If not you will ideally need to replace the balancer, but I have made "temporary" repairs to a spun balancer by very carefully locating exact TDC and making a new mark. I even "repaired" a rocking balancer with 5 minute epoxy -- which I understand lasted for a year and a half until that car was scrapped for other reasons.

Follow Stingroo's instructions. The HB is not subject to spinning on an LO3. If you timed it with the ESC plug hooked up, you will have noticeably advanced timing. If that does not work, the O2 sensor may be following in the wake of the cat. Also check your grounds at the thermostat housing. The grounds are for the computer and the O2 sensor.

Heh. If there's one damn thing I've learned after all these years, it's timing.


...in before Nick. 18436572

Fred Kiehl wrote:

Follow Stingroo's instructions. The HB is not subject to spinning on an LO3. If you timed it with the ESC plug hooked up, you will have noticeably advanced timing. If that does not work, the O2 sensor may be following in the wake of the cat. Also check your grounds at the thermostat housing. The grounds are for the computer and the O2 sensor.

I will bow to your superior knowledge of the L03. The L05 balancer certainly is.

buickwagon wrote:

Fred Kiehl wrote:

Follow Stingroo's instructions. The HB is not subject to spinning on an LO3. If you timed it with the ESC plug hooked up, you will have noticeably advanced timing. If that does not work, the O2 sensor may be following in the wake of the cat. Also check your grounds at the thermostat housing. The grounds are for the computer and the O2 sensor.

I will bow to your superior knowledge of the L03. The L05 balancer certainly is.

If you have had the balancer spin, it is the first time I have heard of on any of the forums I am on. Anything is possible, and it is good to check all possibilities.

It is more common with higher HP motors -- usually after someone does performance mods. However, I have seen stock motors with a sheared key (I suspect the bolt came loose first, allowing some slight movement). It is common enough that you can buy a "pin kit" to fix it (comes with a drill guide fixture to guide a drill bit exactly on the OD of the end of the crankshaft and a pin to drive into the hole).

I'm not saying this is what happened. But it's a quick check to ensure the timing mark is still at TDC. If the mark is off, a timing light is a waste of effort.

buickwagon wrote:

Before setting the timing, check the location of the timing mark against the location of the piston.

If the harmonic balancer has spun the timing mark will be in the wrong spot. It is also possible that the balancer can rock back and forth, which will sound very much like a front crankshaft bearing knock, and is more likely to occur when the engine is warmed up.

If the timing mark is in the correct place, then proceed as above. If not you will ideally need to replace the balancer, but I have made "temporary" repairs to a spun balancer by very carefully locating exact TDC and making a new mark. I even "repaired" a rocking balancer with 5 minute epoxy -- which I understand lasted for a year and a half until that car was scrapped for other reasons.

Dwayne,you own me a keyboard,mines covered with DC!One of my dogs is going to need a bath too,L03 spinning a HB is a good one!

I am surprised by the skepticism. I have seen the balancer spun on a couple of 80's and 90's era stock GM 350s. On one pickup truck, it was spun sufficiently that it would not run at all with the timing set at factory spec, according to the timing mark. On an old Pontiac, it vibrated and sounded like a front bearing knock.

According to Rock Auto, the 91 RMW 305 and the 92 RMW 350 both use the same balancer: 2 piece, an inner and and outer, bonded by a layer of rubber. If the rubber can debond, or the bolt loosen, sufficiently to spin the balancer on a 350, I fail to see how it becomes impossible on a 305.

Your mileage may vary. Check, or don't check, as you see fit.

buickwagon wrote:

I am surprised by the skepticism. I have seen the balancer spun on a couple of 80's and 90's era stock GM 350s. On one pickup truck, it was spun sufficiently that it would not run at all with the timing set at factory spec, according to the timing mark. On an old Pontiac, it vibrated and sounded like a front bearing knock.

According to Rock Auto, the 91 RMW 305 and the 92 RMW 350 both use the same balancer: 2 piece, an inner and and outer, bonded by a layer of rubber. If the rubber can debond, or the bolt loosen, sufficiently to spin the balancer on a 350, I fail to see how it becomes impossible on a 305.

Your mileage may vary. Check, or don't check, as you see fit.

Just making a joke about the L03s well known excess of power before the peanut gallery had the chance.Quite the sense of humor you have Dwayne!

The timing is way off on these jokes,..

Heyooooo.

There he is, lol.

phantom 309 wrote:

The timing is way off on these jokes,..

Que the rim shot...