Does this sound like a thrown rod?

On 14 Jan 2004 15:31:47 -0800, snipped-for-privacy@comcast.net (Bob) wrote:

|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?

do a compression test on each cylinder with a pressure gauge.

You will find out if you have no pressure in 1 cylinder, THEN you have a thrown connecting rod. Until then, it is only a theory.

Lg

If it had actually pitched a rod, you wouldn't have a smooth-running engine at any speed. You'd have a clearly obvious miss from idle to redline.

Likewise, I would expect a thrown rod to make an *INCREDIBLE* amount of noise, not just a "loud ticking". The one time I had a vehicle throw a rod, there was no possibility of mistaking it for anything but exactly what it was. (Did a damn fine job of it, too... #2 rod let go in a '77 Honda Civic. The resulting hole in the side of the block was large enough to stuff a basketball into. And although the car made it to the junkyard under its own power (Don't even think about asking me how - to this day, I haven't got the first clue!) the trip left me almost deaf from the sledgehammer-on-metal noise it made at all speeds other than "stopped")

As you mention, I'd expect a thrown rod to show visible signs: Water in the oil, or vice-versa, cracked/holed block, hole in the pan, and so on. What you're describing, ESPECIALLY the "can rev it up to a certain point then it starts to die out" part, sounds more like a spark, timing, or fuel problem, with my initial long-distance-diagnosis going towards timing. Perhaps you've jumped a tooth on the timing belt/chain, or maybe even more than one. Put a timing light on the beast and see what there is to be seen, would be my first step. At this point, you've got noplace to go but "up" - You've already got one "It's dead, Jim" diagnosis. Taking that as a starting point, you can't hurt it worse than it already is.

Bearings "growl".. So I don't think it would be a ticking noise.. Ticking noise make me think piston slap.

Its possible. I worked on a GM V6 once with a failed harmonic balancer and BROKEN spark plug wires.. (The .080"+ plug gap couldn't have helped.) The entire engine vibrated.. Loud clanking noise.. I thought it had thrown a rod. But compression tests were all basically normal. Ask for the results of a compression test. If one of your cylinders has 0 psi of compression, thats a good indication it needs to be looked at. But I've had everything from a harmonic balancer to a failed fuel injector to a broken spark plug wire cause what you describe.

If the car showed up in front of me, I'd do the following tests:

1. Perform cylinder compression test
2. Perform cylinder Leakage Test

Then

1. Check to make sure fuel injectors were not shorted
2. Check spark plugs, wires, and o-scope engine.

At this point, I'd be able to give you a much better diagnosis then -- simply replace the engine.

__________________ Note: To reply, replace the word 'spam' embedded in return address with 'mail'. N38.6 W121.4

Keep in mind these 2.2's have a history of head gasket problems. (There was a recall on some models).

This engine uses waste spark. If one plug is bad or leaking, it affects the other one. Got a timing Light? Put it on each plug wire and see if it looks the same on all 4. When i found a bad wire on mine, you could see the difference on the timing light. Pull the plugs out and check the deposits on them while you do the compression test. Harbor freight has compression testers on sale this month. I doubt its a rod. I could very well be ignition or a head gasket though. Check it all out before someone's sells you up the river on a new engine.

Bob

I'm no mechanic, but my first thought was a collapsed lifter. I guess I'm asking the rest of the group, but wouldn't this cause a "loud ticking noise"? Also, the compression check would be very low on that cylinder? To verivy, remove valve cover and verify valves are moving (or are not moving) on the cylinder with low compression.

bb

| | |Bob wrote: | |> 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 |> 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.

I think you have a bigger problem with your mechanic. Find a better one. Rex in Fort Worth

| |I'm no mechanic, but my first thought was a collapsed lifter. I guess I'm |asking the rest of the group, but wouldn't this cause a "loud ticking noise"? |Also, the compression check would be very low on that cylinder? To verivy, |remove valve cover and verify valves are moving (or are not moving) on the |cylinder with low compression.

Once the valve cover is off, the noise will be much louder when the engine is running. On many engines you can press the palm of your hand (be very careful) and feel the shock on the offending rocker/cam follower. Heavy leather gloves may be useful, taking care around the spinning cam.

Rex in Fort Worth

suggest you get someone to really check it out. it could be a rod knock, it could be a valve that failed, piston failure, ot such. i'd suggest a compression check, maybe a check on the clearances of the valves. if it's a 'thrown rod' one of the pistons is not going to move up and down. the 'tick' may sound like different things to different people. you really need to check it out it may be something else. good luck, sammmm

you might have bent a push rod. If it's cold were you are like it is here in New England that can happen. Just a thought

I'm assuming this is good news. Just finished a compression check. 1,2 and 3 cylinders are 190, #4 is 185. Am I correct in thinking that rules our internal engine AND cylinder head issues?

If so, think it points to a timing chain problem?

Unfortunately its raining and I'll have to wait until tomorrow to check that.

I'd think so in a heartbeat...

Yes, I'd be *VERY* inclined to think that way.

3 of 4 at 190, with the 4th at 185 is damn good. Most manuals and mechanics I've consulted say that as long as everybody's within 20% of each other, then the engine is well within reasonable. It's a safe bet that your mechanic saw dollar signs instead of engine trouble when he said "thrown rod". Find somebody else to take it to if you don't do whatever work it needs yourself. And trust the mechanic who gave you that diagnosis *EXACTLY* as far as you can throw his garage from now on.

yes, it's good news. the rod is not'thrown'. it may be ready to go, but it hasn't gone yet. the top end of the engine is probably ok. it could be a chain has slipped a tooth. check the timing between the crank and the cam. the check engine light could be from the O2 sensor seeing a bad combustion from the wrong timing. it could be that a timing chain tensioner is bad, too.

good luck, sam

The thrown rods of my experience sounded more like somebody was trapped in the crankcase and trying to break out with a hammer. It can sometimes result in an actual smoking hole in the engine. This is often what people mean when they speak of "blowing an engine." Big bad bottom-end bearing problems short of actually throwing a rod also sound really bad.

Here we speak of connecting rods (piston to crankshaft). If you have an underarm-cam sort of engine you may have thrown a pushrod (cam to valve tappet), or perhaps a valve lifter gave up the ghost, in which case one cylinder would be on the bum. That would definitely explain roughness.

The high oil pressure reading (assuming it's unusual for your car) makes me wonder if there's a bearing problem that is obstructing the path of oil flow.

A cracked cylinder head is not inconceivable.

Anyway, all of these problems call for tearing down the engine to some extent. You might start at the top end, eyeballing the valvetrain area and the head, just to minimize the labor in case you're lucky and it turns out to be something easy and obvious. But I wouldn't operate the engine any longer unless you really yearned for one more diagnostic that required it, lest repairable damage turn into the Big Kaboom and a search for a whole new engine.

Best of luck

--Joe

Does the ticking sound coordinate with one rotation of the crankshaft or camshaft pulley? That could help you isolate it to the reciprocating assembly or valvetrain noise. I know Ford FI engines can sound like they have mechanical tappets from the noise the injectors make. oh, and cuss out that first mechanic you went to.