Clicking noise/ low compresson on #1
 

I may have done a bad thing. First a little background. We were at the MiDiv event in Topeka, running the small pulley for the first time at less than 6000 feet. Boost was in the 14-16 psi range. It's a '99 motor with an Ubercharger, 750cc injectors and an EManage Ultimate. Friday and Saturday had no issues except an occasional splutter at partial throttle. We have been having that off and on anyway. Sunday after the 4th run, it came in making a ticking sound from what appeared to be the valve train. Power may have been down a little and the splutter was worse. The plugs all looked okay to slightly rich. We made three more runs with the ticking getting louder. I elected not to take my fourth run.

I have pulled the belt off the blower and spun it by hand. No noticeable noises.

I removed the valve cover and inspected the springs/lifters. Nothing appears amiss.

Compression test shows 120/160/160/155 dry. I have not done a “wet” test.

Any guesses at this point? What are my next steps? Wet compression test? Leak Down test? ( I am not sure I know how to interpret one and don’t have a tester yet )

Pull the head? Or just go ahead and pull the motor?

Posting on Miata.net as well.

Cylinder w/120 is hurt. Do a leakdown test and figure out what is "hurt". Read this thread:

https://www.miataturbo.net/forum/showthread.php?t=21823

and then check all the HLAs on the 120 cylinder to see if any of them are collapsed or stuck open.

Hi Chris,

What Fuel rail are you using with your 99 Motor and is it single or Dual Feed? I've heard from Multiple people with 99-00's who have had #1 get low on compression and have usually seen signs of detonation when they tear the motor apart.

This is one of the reasons for our Dual Feed Rail, and even why we like placing the dampener on an NB in the middle of the rail.

That and a "wet" compression test are next on my list.

It's a '99 motor so it has solid lifters, although I could have lost a shim which would account for the noise, but not the loss of compression. I didn't find any "extra" parts when I pulled the valve cover.

I am running the '99 rail converted to return style. It still feeds from the back, but returns the fuel from the front to the tank. When we pulled the plugs Sunday morning things looked fine. The plugs i just pulled all appeared rich.

Thanks for all the suggestions. I will do some more testing tonight and likely just pull the head. I am wondering if perhaps a rod bent a little. I plan to check the valve lash before I pull the head as well. I am having troub le accounting for the clicking. A bent or burnt valve would likely loose more compression wouldn't it? Does a bent rod click?

Wait till leakdown to pinpoint for sure if it's the block or the head.
I can see it being a slightly bent rod.
One more reason to go with a bigger bore dual fuel rail ( ;) Marc)

Do you have a form of knock sensing?

I bet it was really high intake temps combined with knock.

What the highest anyone has ever safely run a supercharger on our engines?

I was going to vote shim, but figured you could have seen that when pulling the cam cover. Though, I have seen the shims split and that might also cause valve issues. I hope for your sake it's that simple. Clicking definitely sounds better than knocking. ;) Good luck.

I'm throwing this out there just for the sake of suggestion, but the donor block I'm using in my build had a loose rod cap and bearings in cyl #3 and would "click" when the piston reached TDC and then started it's movement downward. Not sure how that would affect your compression though, unless you already had an issue there.

If you're pulling the head and don't want to pull the engine yet, the best way to test for a slightly bent rod would be to turn the crank by hand and make sure that each piston is reaching full TDC and evenly. And I found that the way to test for the bearings is to get each piston to TDC, then turn the crank slightly to get each one to just barely start moving downward, and see if you can push the piston down any by pressing on top of it with your hand. If it moves down at all, it's going to be a bearing/cap. Also make sure piston 1/4 and 2/3 move perfectly with each other. Sorry if you know this information already, but it's a test I just used on my car and donor block and was very effective.

Thanks for the input guys. I still have to check valve lash and do a leak down test before I pull the head. Hopefully I will get to it tonight.
It would be nice if it were a shim, but it's hard to picture that causing the compression issue.

I don't know if a bent rod clicks or not. Anyone have an idea?

This was supposed to be the last event on the EMU. The MS-II and Knocksense are sitting on my desk. Oh well.

One other data point, it's a FOUR MONTH lead time if you want a 2.0 stroker from FM. ( just looking at options for the worst case scenario which is probably a rod)

I think a bent rod would only click if it were bent so bad that it's contacting something. But if that were the case, it would look like mine did, and your engine would probably not be running at all.

Chris,

Hurt bearings, loose rod caps and a bent rod could all possibly cause "a click".
Without tearing the engine down, you should still be able to diagnose a piston that is not "coming up all the way". A dial indicator with a long extension and a sparkplug adapter should enable you to make relative (not absolute) measurements of how high each piston goes in your engine. If your 120 cylinder is "lower" than the other 3, you may have a "rotating problem".

I'd still do the cylinder leakdown test first. With that done, you'll be able to see if you have leakage past the the rings (broken ring lands, hole in piston, cracked piston), the intake valves (valve or guide) or the exhaust valves (valve or guide).

I agree with your hypothesis that is unlikely that a solid lifter shim could have "skipped the bucket" and caused the clicking or loss of compression problems (My bad in prior post on HLAs, didn't realize that you were one of the "lucky ones" with solid lifters)

FWIW, I really don't know how anyone can cost justify a FM 2.0 stroker! Get a set of H beam forged rods, a good set of forged pistons and spend the difference on a full ball bearing GT turbo with a good tubular manifold and external WG piping...I think you'll be way ahead...but YMMV.

I agree with the rods/pistons, but why would I want a turbo?:)

The FM motor might have been a quick option. I have about 6 weeks before the car runs in the SCCA Solo II National Championships, and way to many other commitments in between.

I was rotating the motor by hand last night doing a leak down test (which I either did wrong, or it didn't show anything significant) and found that things got really hard to turn as the #1 piston reached BDC.

I will tear more of it apart tonight and over the weekend so that I at least have a diagnosis and parts list by Monday.

[QUOTE=Chris Swearingen;293877]I agree with the rods/pistons, but why would I want a turbo?:)

Ooops forgot you were a "blower guy"...bag the stroker motor, add a Meth kit and have enough let over for a lifetime supply of methanol :)

sn95, Chris already has WI, though at present it's a simple on/off system, no controller.

Chris, sounds like you're on track. You've got a bad noise, and some funky datapoints. You know it's not on the topside, so the head's coming off. Once that's done, you'll be able to visually see the problem- either a piston's gonna be burned or one of 'em ain't gonna come up to the same height as the others. Resistance while turning isn't encouraging- plugs out, I assume?

THAT sure sounds like a rod. I was going to say valve lash (just cause I have that issue myself, skipping cyl and a ticking sound - though that tick might be unrelated) - but what you're describing is EXACTLY what I had when I bent a rod a long while back.

The rod bent enough the piston skirt contacted the crank counterweight. Low compression on bent rod cyl, and very hard to turn at the bottom (stretching rod slightly). I've bend rods twice, both times I could tell just by putting a dowel in the sparkplug hole, turning the motor over and seeing how high the rod gets at TDC each one.

I'm not sure what the EMU you were running does, but the last time I lost a motor, it was that - bad handling of altitude.

I have prevoiusly diagnosed a bent rod before by taking a long screwdriver placing in each cylinder and made a mark on screwdriver once reached top dead cylinder in cylinders that compression was good in. Then checked low compression cylinder and was not the same is not very accurate but worked for me. We were pretty sure it was rod because compression was low in one cylinder but leakdown was good in all cylinders.

Good luck maybe it will be something minor but doesnt sound like it.

Yay! I'm not alone in thinking the stick test will work. :-)

Anybody else think these pistons should be at the same level?

Looks like a rod to me. I will get pictures of it after the motor guy disassembles everything for measurements Monday or Tuesday.
http://www.systemstrategies.com/miat...od/bentrod.jpg

I sense an upgrade in your future!

Unless you were already upgraded. Either way, I do forsee unavoidable expendetures. :-( Hope the rods are all that's bad.