Engine Noises - Back to square 1

sts70004

Registered User
So I recently changed the metal plate between the engine and tranny on my 89 SC because I bent it repairing the rod knock I got at 150,000 miles. After reassemble the first time, it was just a tick, that turned into a rattling/knocking noise over time. After changing the plate, no luck, still the same noise. I need some help diagnosing the noise. Heres what I have so far:

Knocks around 2500rpms or so when not moving
Ever now and then I hear squeaking when accelerating in 1st gear only at low RPMs

My ideas are:
-Lifter/Valvetrain
-Throw Out Bearing (has 20,000 miles on it currently, Autozone brand though)
-Rod Knock (I'm REALLY hoping its not this one)

How can I test these?
 
Posting a video would be very helpful. It would also be helpful to know what measures you took in repairing the rod knock. Did you simply install earrings or did you send the crankshaft out to be machined, did you also replace the oil pump, etc.

I am not trying to be negative but 2,000 to 2,500 rpm is about when a rod knock would become present on these engines while out of gear.

If you had some rod journals that were scored or out of spec and you simply installed new bearings then I would say the scored journals ate away at your fresh bearings.

I hope I am wrong for your sake because I know it took quite a bit of work to fix it the first time.


If you want to test for a rod bearing. Simply disconnect one plug wire at a time from the coil pack, restarting the engine each time. Bring it up to 2,500 rpm and see if the noise goes away. If it does then it is a rod bearing and the plug wire you pulled is the cylinder with the rod knock.
 
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Ouchie. Sounds like a rod to me. When you did the bearings was one of the bearings spun out? The reason I ask is that when that happens typically the connecting rod needs to be reconditioned.

I do not believe the oil pumps fail in these cars often at all. I was just asking what had been replaced when you did this work. Curiousity was all. :)

I am sure the crankshaft and bearings you got from Dave were good. There are many reasons why this could have happened but I believe this to be a rod knock.



Robert
 
I rebuilt an engine once cause the bearings got cooked. We put a real oil pressure guage on it after the rebuild and as the rpms went up the oil pressure went down. Ended up being the pick up tube had a crack in it and was sucking air. Might want to check your pressure. Definatly sounds bearing related.
 
I know it's not even close to accurate, but I put a mustang oil sender on the engine and it's reading plenty high. Your guess is as good as mine on what the actual pressure is. If its a rod again, I might give up on the v6 :( or rebuild and go for broke lol. I'll test the plug wired and report back
 
I can't hit your link from work, but I had a noise that developed on my 95 shortly after rebuilding it and racing it a couple years ago. Thought it was a rod knock but turned out that my flywheel bolts had loosend up on the crank. I never lock-tightend those bolts before, but I do every time now. Pull that sucker back out see what happend! Let your and our curiousity drive you foward. I would check oil pressure first with a manual gauge though.

chris
 
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Well I'm currently working so I cant test yet, but I don't think its the flywheel bolts, I JUST installed them, less than a mile ago.
 
Ouchie. Sounds like a rod to me. When you did the bearings was one of the bearings spun out? The reason I ask is that when that happens typically the connecting rod needs to be reconditioned.

I do not believe the oil pumps fail in these cars often at all. I was just asking what had been replaced when you did this work. Curiousity was all. :)

I am sure the crankshaft and bearings you got from Dave were good. There are many reasons why this could have happened but I believe this to be a rod knock.



Robert

I tend to agree with 90sc35thann. I listened to the video and as far as I can tell you have a engine rod knock issue.

Could have been some metal chips left over after you repaired it... I would take a mechanics stethoscope to it and if it is in the engine.
 
Can't the relief valves in the timing cover on these jam up causing a drop in pressure? That design with the relief valve integrated in the timing cover scares me.
 
I had the crank turned .010. New bearings from xr7dave. Did not replace the oil pump. Didn't think that had a high failure rate. On a side note, engine has 166k on it

http://www.youtube.com/watch?v=YyM1GOb9siE&feature=youtube_gdata_player

Sorry I just noticed you only got the bearings from Dave. When you had your crank machined did you have the mains turned .010 as well? If so did your machinist know that the rear main journal is already .010 undersized? Also when you install the main bearings in the rear crankshaft journal did you use the correct bearings?
 
The big question is did you check bearing clearances when you put it together? With a turned crank you should have nice tight consistent clearances. I use plasti-gauge to check that.

Chris
 
The big question is did you check bearing clearances when you put it together? With a turned crank you should have nice tight consistent clearances. I use plasti-gauge to check that.

Chris

I usually use a micrometer on the journals and plastigauge. Plastigauge alone isn't overly reliable. I have seen that stuff screw up.
 
I did remove the blower belt, plastigage is what I used, I don't know about that rear main bearing but the plastigage put me in the "optimal" range according to my service manual. I'm gonna pull the plug wires tomorrow and check. Halfway moved to a new house so I'm busy lol. It does sound awfully high in the engine but I haven't grabbed a hose to test this. I think I'm gonna tear down the top end in hopes of a bad rocker or bent pushrods/valves. If its rods, how hard is it to get a 5.0 running in these cars with all the features like arc and abs still working?
 
Don't tear down the top end, that's going to be a waste of time. Get an oil pressure gauge and check pressure. It is very common for the relief valves in the timing cover to stick, especially if you didn't replace it.

Check oil pressure with a real gauge before going any further.
 
I did remove the blower belt, plastigage is what I used, I don't know about that rear main bearing but the plastigage put me in the "optimal" range according to my service manual. I'm gonna pull the plug wires tomorrow and check. Halfway moved to a new house so I'm busy lol. It does sound awfully high in the engine but I haven't grabbed a hose to test this. I think I'm gonna tear down the top end in hopes of a bad rocker or bent pushrods/valves. If its rods, how hard is it to get a 5.0 running in these cars with all the features like arc and abs still working?

The rear main journal is unique and uses unique bearings. The main bearings for the rear journal should have been marked or had unique part numbers. There is usually a piece of paper in the box describing which bearings are for which jourinal. If you didn't take notice to this it could cause oil pressure issues resulting in rod bearing noises.
 
Don't tear down the top end, that's going to be a waste of time. Get an oil pressure gauge and check pressure. It is very common for the relief valves in the timing cover to stick, especially if you didn't replace it.

Check oil pressure with a real gauge before going any further.

Or like Dave said the relief valve could be stuck as I also eluded to in an earlier post. :)
 
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