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Does this sound like a thrown rod?

Have a prob with my 97 Sonoma 2.2 5 speed 106,000

Whole thing started a week ago today. Noticed a ticking noise from the engine area. Headed straight to the mechanic who diagnosed the problem as a worn bearing on the belt tensioner. Ordered the part and told me it was ok to drive until Monday.

Last Friday check engine light came on. truck was driving ok but seemed to lack power. Nothing too serious just felt like it had less power. Decided to head back to the mechanic. On the way truck suddenly started what I can only describe as a loud 'ticking' sound from the engine compartment and had basically no power. Engine idled very rough, didn't stall but was very rough. Shut it down and had it towed in. Mechanic started it up listened for 10 seconds and said, 'you threw a rod, need a new engine'. I had it towed back to my house because that kind of expense is just not in my budget.

Spent the past few days doing research and I have a few questions. I went out today and started it. Still the loud ticking, doesn't seem to change much with engine speed. Idles rough, engine speed increases as I apply gas but only to a point. Then it starts to die out. Almost like its not getting enough gas or something. Engine actually sounds fairly smooth as long as I don't give it too much gas. As the rmp's get higher the loud ticking seems to be much less. Oil pressure is 45 at idle and rises to 65.

Is it possible the check engine light and initial power loss was caused by an obstruction in the exhaust system (ie: blocked catalytic converter) and the other noises are a result of back pressure. I just expected a thrown rod to be louder, maybe make a hole in the block or have water in the oil.

Any suggestions?

Reply to
Bob
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Bob,

Do you have any way to record an audio clip and post a link to it?

Jeremy

Reply to
Jeremy Chavers

Doesn't exactly sound like a connecting rod from your description. Could be a bad valve. B

Reply to
Battleax
!

Pull the plugs, Stick a finger over the hole and see if you feel compression on each cylinder. If you dropped a cylinder you won't find compression on at least one. Now to determine if you did throw a rod look into each spark plug hole and see if you can actually see the piston (haven't messed with a 2.2 much) moving. If they all seem to be moving then you may have dropped a valve, or a lifter may have failed.

Steve W.

Reply to
Steve W.

Reply to
retorq

I think if it's an actual thrown rod, 99% of the time the engine will absolutely not run. The rod and piston seperate from the crank and mash valves and/or the crank. I'd imagine if the engine was able to run, that it'd vibrate noticeably from being out of balance.

It's real hard to say what the problem could be without hearing it... If it's in the bottom end of the engine, you'd hear a noise every revolution. If it's in the top-end (valves, lifters, cam), it'd be at half the engine speed.

My guess from here would be something in the top end of the engine, like a dead lifter or bent pushrod. I don't think there's any other types of "issues" that would normally allow the engine to run without completely self destrucing.

-marc

Reply to
Marc Westerlind

Also, Any way to pull the code off the computer?

-marc

Reply to
Marc Westerlind

Usually a rod will knock TWICE per revolution

Reply to
Gary Glaenzer

snip

My snowblower blew a rod last winter. It (some of it) exited just below the starter motor and landed in the snow, then melted it's way out of site. Most spectacular. B

Reply to
Battleax

Just finished the compression check. 1,2 and 3 cylinders are 190, #4 is

185. I'm assuming that's good news and rules out internal engine and cylinder head issues.

From what I've gathered on various boards I'm thinking the prob is actually with the timing chain. Possibly slipped a gear if the tensioner went bad? For all you experts out there.....sound like I'm on the right track?

Unfortunately its raining and I won't be able to dig into that until tomorrow.

Thanks again for everyones help.

Reply to
RAM

Timing chain is the next step in this diagnosis. b

Reply to
Battleax

Wouldn't he have a pencil-sized object or a small dome about the size of a marble in his valve cover? Unless it went out the bottom. I know a Chevy will run with bent rods. I had a retard of a mechanic replace a thrown timing chain on my 307CUI and it took him 30 minutes to start it, but it started with 4 bent rods and 1 shattered. Not to mention bent valves.

~KJ~

Reply to
KJ

When my 4.3 did this it was carbon buildup in the combustion chamber. The dealership let it warm up then with high RPM one guy poured about a half quart of transmittion fluid down the throttle body (don't let the engine die) to dissolve the carbon. Sure cured my thrown rod in a hurry. It may not work for you but I'd give it a try.

Jerry

Reply to
Jerry Stockton

Don't know about the transission fluid but I've used parts solvent already (not really recommended) and also poured Marvel Mystery Oil down the intake. The Mystery oil worked for me but the smoke coming out the exhaust is worth mentioning (as in it will smoke like a cheap cigar for about 10 miles. Some guys use ice water. The ice water works by thermally shocking the deposits and knocking them loose. Regardless of what you use, you've got to pour it in VERY SLOWLY. If you pour it too fast, the engine will hydraulic and could suffer some severe mechanical damage.

Reply to
Rich B

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