Engine ticking noise - spun rod bearings or worn valve springs?

[mildundersteer]

I have 2003 Protege5 Automatic at about 150000 miles, the original engine, no mods. I sort of drove hard on twisty backroads, and the engine developed metallic rhythmic ticking noise correlating the engine speed. I'm thinking it's worn valve springs or spun connecting rod bearing. I've done valve stem seal replacement on older Toyota 4 cylinder engines while the engine still in the car, so it wouldn't be too hard for me if that's the case, but I've never done rod bearing replacement. Can anyone point me to good threads or links that explain how to do it without taking the whole thing out? I have Mazda shop manual but no instruction for this method. Preferably a step by step instruction possibly with some photos will be great. I read somewhere in this forum that transmission needs to be separated from the block but I can't find the instruction.

 

[P-Funk!]

Perhaps it just needs a cam/lifter adjustment.

Have you listened (with a stethoscope or socket extension) where the noise is coming from yet?

 

[mildundersteer]

I listened to many spots wherever I can stick the stethoscope through, the cylinder head and the block. It did sound the loudest at the cylinder head near #3 cylinder.

So, I opened up the cam cover and checked the valve clearance, and there are several that are out of spec, two of #3 exhaust, two of #4 exhaust. While the max clearance is 0.0116 in, these don't take 0.013 gauge but take 0.012 gauge easily. So I guess I'll do the whole valve adjustment deal while I'm at it.

However, would that much of off clearance make unusual noise? The car was running really good without any unusual noise, it still doesn't burn oil or smoke, no leak, and the ticking started immediately after driving hard repeatedly revving at 6000 rpm while cornering. Would the valve noise develop like that? Wouldn't it rather develop gradually?

Also, did anyone ever have to replace valve springs for street applications?

Additionally, I don't know if it's related to the above valve clearance issue but on the cam cover, around the cam cover bolts near #3 and #4 cylinders and #4 ignition coil I see some soot seemingly leaked out of the cylinder head. It's not oil stain.

 

[P-Funk!]

No valve spring replacements have needed on stock engines...

Button it up and see if that fixes it (I can't think of anything else since you ruled out a noisy injectors...)

Check spark plug torques 'just in case'.

 

[mildundersteer]

Thanks for your feedbacks.
Spark plugs check out fine. I didn't think about the injectors but they feel they are sitting ok, by gently wiggling them by the connectors, I'm not sure.
Considering the noise speed increase along with rpm, the engine internals are still most suspicious to me. I ordered new shims at Mazda and will see if the valve adjustment will fix this issue this weekend.

 

[The_big_dill]

I doubt its a spun rod bearing.

The P5 has solid lifters, so that would be a contribution to the sound since you mention its out of spec.

 

[mildundersteer]

Well, I installed adjusted valve shims and all seem good but that didn't fix the noise.
I found that #1 spark plug tip is smashed and now I'm learning about the intake butterfly screw thing?
I'm not sure noise is from the loose butterfly or something got in the combustion chamber. But the noise is steady and gets faster with rpm, so I still think it the engine internals but if you could let me know more things to check, I'd appreciate.

 

[The_big_dill]

Well, I installed adjusted valve shims and all seem good but that didn't fix the noise.
I found that #1 spark plug tip is smashed and now I'm learning about the intake butterfly screw thing?
I'm not sure noise is from the loose butterfly or something got in the combustion chamber. But the noise is steady and gets faster with rpm, so I still think it the engine internals but if you could let me know more things to check, I'd appreciate.

Can you record the noise on camera?

Did you check that it fell off the butterfly valve?

I just had my P5 eat one of those screws and it sounded like marbles in the engine, the sound was not just a slight ticking, it was horrific. It bent the electrode to 0.001" gap and resulted in a none sparking fouled plug, which meant a mis fire and very rough idle. I replaced the plug and the screw only bounced around for a few revolution and left the combustion chamber... I have yet to check compressions but my fingers are crossed.

 

[P-Funk!]

A borescope is now only ~$75 at Walmart...

 

[mildundersteer]

What happened was when I put the timing belt back and all and started the engine, it started right up and good but then the engine warning light came on, #1 cylinder misfire. So I checked the spark plug and found the faulty tip.

I didn't hear that "the screw-bouncing-around" noise. It might have just came out of the chamber before I noticed it.

The noise has always been somewhat louder ticking noise, not quite "clank clank", but somewhat louder than valve noise I've heard before, but the steady ticking increacing with rpm made me think it could be the valves and my mechanic agreed. I recorded the noise and I'll have to figure out the best way to post it.

At this point I thinking it's even possible that the ticking it's been suffering and the valve screw are separate issues. I guess there is only one way to find out. First I plan to open up the intake manifold and see what's up there.

Addly, I called Mazda corporate customer service, and they say that based on the vin, my car had already received the recall repair back in 2006. It sounded like they would've still honor the recall if my car didn't recieve the repair back then. If your car is having an issue related to the recall 3005C (intake shutter valve), try the Mazda corporate and you might still be able to get help from them. Mazda USA 800 222 5500.

 

[mildundersteer]

So I took the intake manifold open. It turns out it's the case of VICS screws coming off. Both of the cylinder #3 screws are out, the butterfly was found at the bottom part of the runner. One of #4 screws is gone, the other one is almost off and the butterfly is dangling loose. I can imagine this could made some nasty noise. Screws for #1, 2 are still on but loose as well.

All the VTCS screws are nice and tight. What was Mazda thinking?

I can't explain why these #3, 4 screws messed up the #1 spark plug. They must've fell to the bottom part of the manifold and lead to the #1 cylinder by the air, I guess.

I ordered the intake manifold gasket kit supposedly including the screws, but the dealer parts guys weren't sure. If I can't get the screws from the dealer then where do I get them from?

Anyways, once I get those screws, instead of taking the cylinder head out and do the deed, I plan to put them back together and hopefully everything will be good. I haven't done the compression test yet though. Fingers crossed.

 

[The_big_dill]

There was a recall on the manifold. Make sure you put some loctite on those screws.

 

[mildundersteer]

OK. So I got the VICS screws fixed. Now the noise is somewhat partially quieter, but the noise is still there, bit more "muffled" than before.
Now I came across this youtube video and my car sounds a lot like it. And the video is supposed be the noise from spun rod bearings.

http://www.youtube.com/watch?v=5TcIu9djhWc

So I guess I'm moving on to replacing the rod bearings. And I don't feel that the entire engine takedown is economically sound for the value of the car itself as I don't have the engine crane and stand and stuff and hoping to do this by removing the oil pan from under the car, without taking the engine out.

So, what are the chances that the crankshaft and/or connecting rod are damaged? Where to look?

And if I were to replace the rod bearing under the car, could someone advise or point me to good threads for tips for this procedure by someone actually done this before. I have the engine support I use for replacing the engine mounts and I'd think that'll be enough support after transmission bolts are removed but exactly which transmission bolt needs to be removed? all of them?

 

[mp5la]

I think it would be 150% worth it to get an engine crane for this job (if that is in fact what's wrong). I can't imagine trying to do this from under the car even with a lift.

 

[mildundersteer]

You would take the engine and transmission out of the engine bay together, or just the engine?

 

[tweety2300]

You would take the engine and transmission out of the engine bay together, or just the engine?

If you have a hoist pull them both out together. Way easier

 

[mp5la]

Agreed. Getting the trans out on its own sucks.

 

[mildundersteer]

Thanks. Mine is the automatic, but the the same applies, correct?
This started sounding like a bigger job than I hoped.

 

[mildundersteer]

In case anyone is interested, here is the update.
It seems that the noise issue was the combination of the connecting rod bearing and the VICS screw stuck somewhere in the cylinder head.

Thanks to info from fellow members, I was able to replace the rod bearings without taking the engine off the car. I didn't see anything unusual except the #3 cylinder rod bearing just fell off the rod when I unscrewed the rod cap. I don't know if you'd call it "spun" but it was loose I suppose. I replaced all the bearings anyways, no sign of internal damage. After that, the "clank, clank" noise was gone, but the steady knocking-like noise on the cylinder head remained.

While wondering what was wrong since I've already done sim adjustments, I drove the car to a car wash because I couldn't wait to wash off two month worth of dust. Maybe, just maybe I thought it could still be the VTCS screws, so I revved a couple of times, then, it passed! Like a kidney stone, followed by "tink tink" sound assuming the screw dancing around in the combustion chamber, smashing the #4 spark plug eletrode.

I haven't opened up the cylinder head yet, but my guess is that the screw somehow got sucked in the valve train and stuck there until now?

Anyways, the car is running better than ever due to all the things I ended up doing, such as cleaning the intake/ egr valve, remounting the VTCS valves, valve sim adjustments, etc.

I plan to check the valve train, maybe replace the valve stem seals might as well, when I get a chance, but this was the update.