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PostPosted: Sun Aug 10, 2014 7:08 pm 
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Hi, I'd posted this over on GT4OC but not getting much reply at all, thought I'd post it up over here and see if anyone has any ideas.

I've got this very marble sounding knock which sounds to me & my mate, like 100% bottom end knock.

However the con rod bearings have been replaced 3-4 months ago. I thought the knock had gone after I'd replaced them, however maybe it didn't I can't be sure. Anyway, yesterday I stripped off the sump again and inspected the con rod bearings again expecting to find them knackered, to my surprise they all look brand new still, so I measured the clearances with some plasti gauge.

All 4 clearances were between: 0.025 & 0.038
Now toyota standard clearance is 0.024 - 0.055 ( Max clearance : 0.080 ) - so they are all well within the standard spec and way inside the max limit.

I also inspected the number 3 main bearing, which looked brand new and was well within clearance specs. ( if these have been replaced before I've got no idea, but I've got no receipts or anything that suggest they were ). I didn't inspect the rest of the main bearings as I figure they wouldn't knock even if they were worn and judging from number 3 bearing they are not even close to being worn anyhow.

So I'm completely lost as to what this noise is.
Goes away when warm
It's noticeable on idle when cold, more so when you blip the throttle, seems to pick up with the revs.
Sounded HORRENDOUS when I putting my car up onto the ramps to work on it.
Seemed to go away when the drivers side was jacked up..... ( something to do with oil I guess ) Don't really know what this suggests.
Sounds very bad underneath, which is why I was almost certain it was big end bearings, having had them go on a previous GT4.
My oil pressure is up at around 70psi when cold idle, drops to ~20psi on idle when warm. ( I think this is normal running conditions )

There is side to side movement on number 4 rod that seems to make a noise very similar to the sound I can hear when it's running. Side to side movement is normal though isn't it? Where does this movement come from, will it be the wrist pin?? The others all have side to side movement to0, but the sound is not as pronounced as number 4, which makes me think 4 has more side to side movement than the other 3 rods.

Anyone got any ideas. Am I looking in the wrong place? Can the head make a marble knock sound from the cams hitting the buckets? I've not checked head condition....? I've always assumed the marble sound comes from the type of material that the crank is made from, which I assume is the same as the cam shafts? So I was thinking it must be crack shaft hitting something or cam shaft hitting something....? Is that right?


Any tests I should do? Compression test is like 170-180 on all 4 cylinders.

Any thoughts???
TIA.


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PostPosted: Sun Aug 10, 2014 7:08 pm 
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Okay, some pictures and vids to show what I've found.

Here are the bearings ( less than 10K done on these... )
2 is worst one and 1 is not far behind. 3 and 4 seem fine compared.
All the bottom halfs are fine, they look almost new. It's just the top half of the shells look like they'll be fubar before long....

1
Image

2
Image

3
Don't have picture, but was like 4.

4
Image

Videos of end play.... 2 sounds very different to the other rods. It sounds very similar to the noise while running.
I double checked the clearance with plastigauge again, it's between 0.025 & 0.038 so well within spec still ( checked top and bottom of journal )

End play rods 1 & 4 : View My Video
End play rods 2 & 3 : View My Video


Any thoughts, is that amount of end play normal?

The limit for end play appears to be 0.35MM from the manual. I couldn't fit a .35MM feeler between the rod cap and crank, mostly 0.25MM max, some even 0.20MM


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PostPosted: Sun Aug 10, 2014 10:28 pm 
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Have you checked for crank endfloat ? Does the noise get louder / quieter if you put a little pressure on the clutch pedal ?

Do you have a recording of the noise ?

What spec & history of the engine ? Is it forged ? if so, is it the new JE pistons that foul the squirters ?

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PostPosted: Sun Aug 10, 2014 11:03 pm 
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Crank end float due to worn thrust washers? I'm not sure how to check this, do I just pry the crank gentley to see how much it moves?
Unfortunate I don't have a recording, it sounded similar to when I had rod knock before on my old ST205 though. That kind of loud bad sound that you know is something nasty.

The engine in standard internally as far as I know. 140K ish, I've owned it for a few months now ( owned a ST205 before for 7 years though ).

I don't know if pressing the clutch was making a difference as I wasn't paying attention really, but when putting the car up onto ramps, which of course puts quite a lot of load on the engine and requires holding the clutch quite a lot, the noise was horrendous, it was at it's worst when I was trying to get the front up on the ramps.

The main points are, cold start can hear the noise, goes away when fully warm.
Blip the throttle a bit when it's idling and cold and the noise gets worse, like it changes with the revs. Maybe 1.5k its quite noticeable.
When the car was jacked up on the drivers side the noise was less noticeable, this must be something to do with all the oil being tipped to passenger side while jacked up, soon as lowered it down on the drivers side the noise became more apparent.

I'm at loss :(


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PostPosted: Mon Aug 11, 2014 12:53 am 
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From your description it sounds like your engine originally developed a knocking sound and you have then subsequently replaced the big end bearings thinking that this was the source of the knocking sound. Is this correct?

What was the engine oil like before you changed the big end bearings? Was there any sign of metal in the sump? Did you carry out a full engine flush to ensure there was no debris left in the engine before you replaced the bearings? Normally if the big ends go on an engine you would check the crank pins for wear and regrind them as they almost always suffer some wear damage. As I don't have the equipment to check all of this myself I would get someone reputable to do the measuring and machining work. If it was my engine then this is the procedure I would follow but it does take more time and effort, not to mention cost. In my case I considered it worthwhile if only for the peace of mind it gave me!

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PostPosted: Mon Aug 11, 2014 1:33 am 
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Are those pictures the "new" bearings?
The top shells look melted and there's some obvious weird wear around the squirter hole
I'm also seeing what looks like contamination damage on the bearing surfaces. I'm wondering if there's an oilway blockage issue

The only other thing I can imagine is the timing is overly advanced.


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PostPosted: Mon Aug 11, 2014 8:53 am 
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two_OH_five wrote:
Are those pictures the "new" bearings?
The top shells look melted and there's some obvious weird wear around the squirter hole
I'm also seeing what looks like contamination damage on the bearing surfaces. I'm wondering if there's an oilway blockage issue

The only other thing I can imagine is the timing is overly advanced.


Yes the pictures are the 'new' bearings. The ones from rods 1 & 2 are both showing those signs of weird wear, 3 & 4 both look normal to me.

I did notice that there is a SARD ECU fitted, maybe that's advancing the timing too much.... I'm tempted to remove it and fit my Blitz ECU from my old car which I know is good, or even standard ECU.
I did wonder if there was some kind of blockage, however from all the bits I can see the oil passage ways look very clean, obviously I can't see everything though because the engine is still in-situ.

TrackToyFour wrote:
From your description it sounds like your engine originally developed a knocking sound and you have then subsequently replaced the big end bearings thinking that this was the source of the knocking sound. Is this correct?

What was the engine oil like before you changed the big end bearings? Was there any sign of metal in the sump? Did you carry out a full engine flush to ensure there was no debris left in the engine before you replaced the bearings? Normally if the big ends go on an engine you would check the crank pins for wear and regrind them as they almost always suffer some wear damage. As I don't have the equipment to check all of this myself I would get someone reputable to do the measuring and machining work. If it was my engine then this is the procedure I would follow but it does take more time and effort, not to mention cost. In my case I considered it worthwhile if only for the peace of mind it gave me!


The crank journals show no signs of obvious wear, yes in an ideal world you would polish the crank and have everything checked by a machine shop. They feel very smooth running my nail over them, overall looks in good condition given the age. There was not any metal in the sump when I replaced the bearing before, I mean there was the normal particles that you can see, very tiny, but not the kind when a bearing gets chewed up and you get chunks of bearing in the sump, that wasn't the case. The bearings were worn, but they were showing signs of just normal wear from age, not anything bad.

Can I do some kind of flush with the engine in situ, just to be sure?

I have 3 ST205 engines, but 2 in my garage and I am planning to forge one - full rebuild. But this car is my daily drive so I would like to resolve this issue if possible so that I can continue to use it while I take my time rebuilding one of the other engines. I stripped it down because I didn't want whatever is knocking to do some permanent damage to the engine in my daily drive that would mean I had to stop using it until my rebuilt 3sgte is ready.


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PostPosted: Mon Aug 11, 2014 11:01 am 
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Did the old bearings look the same when you replaced them?

For the absolute avoidance of doubt is number 1 gearbox end or cambelt end

Any non oem bits - lightweight flywheel, alloy pulleys etc

I think I'd pull and check all the mains, especially up the end where this weird wear is happening worst

Check each piston journal web (hope that makes sense) for signs of wear. Check the sides of the rods for signs of wear. If the knock is a rod contacting the crank there will for sure be witness marks

While you've got the ends apart have a tug on the rods and see if you can feel any play in the little ends

Pull #3 main and check the thrust washers for wear (you'll only be able to check half of them). You check endfloat exactly as you thought.

I think I would also try to poke something suitable up the conrod drillings.

I'm trying for the life of me to remember how oil flow through the crank works. During my rebuild I flushed through using a fuel pump and aquarium air hose to pump cleaning fluid via each drilling main bearing drilling but now I've forgotten what came out where

It certainly looks odd to me, I suspect an oil flow issue but I'm not sure. I would expect signs of blueing on overheated oil starved bearings


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PostPosted: Mon Aug 11, 2014 3:28 pm 
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two_OH_five wrote:
Did the old bearings look the same when you replaced them?

I have them at home, could post pictures later. The top half of the shells were all noticeably more worn than the bottoms. I think this is a sign of some detonation??

two_OH_five wrote:
For the absolute avoidance of doubt is number 1 gearbox end or cambelt end

I'm calling number 1 as in number 1 cylinder, which would be cambelt end. So the 2 that are showing signs of melting are the two closest to the cambelt side.

two_OH_five wrote:
Any non oem bits - lightweight flywheel, alloy pulleys etc

None that I am aware of, pulleys are standard. Flywheel looks like the standard heavy *bleep*.
It's worth noting though that when I had the crank pulley off to do the cambelt I found a chunk of it missing, presumably where it had been dropped on the floor when previously removed. This would have certainly put it out of balance, what effect that would have and how long it was like that I don't know. I have now replaced it though so it's not still on the car. I couldn't believe someone would refit it in that condition....idiots.

two_OH_five wrote:
I think I'd pull and check all the mains, especially up the end where this weird wear is happening worst

I've pulled 3 and 5 already, but 5 is the opposite end to the worn rod bearings, I'll pull mains 1 & 2 and check them, good idea!

two_OH_five wrote:
Check each piston journal web (hope that makes sense) for signs of wear. Check the sides of the rods for signs of wear. If the knock is a rod contacting the crank there will for sure be witness marks

There did appear to be a few wear marks on the sides of the caps & rods, I presume this wear suggests the crank is moving side to side which points to excessive end-play. I'll check end-play later for sure.

two_OH_five wrote:
While you've got the ends apart have a tug on the rods and see if you can feel any play in the little ends

I did try this and I couldn't feel anything, I expect it would be quite obvious if there was wear to the pins as there would be a noise when I wiggle them up and down?? I also did a little twist from side to side and there didn't seem to be any play, of course the piston turned too, but it all seemed very secure and fixed tight.

two_OH_five wrote:
Pull #3 main and check the thrust washers for wear (you'll only be able to check half of them). You check endfloat exactly as you thought.

Thrust washers are quite loose, I'm not sure what they are supposed to be like but I noticed this when I had #3 main cap off. I could touch them with my finger and they would move round with ease ( I'm talking about the tops, not the ones that come off with the cap ). Will of course check end-play to find out if they are too worn.

two_OH_five wrote:
I think I would also try to poke something suitable up the conrod drillings.

These are the small holes in the rods, I presume to allow oil into the top of the shell?

Thanks for all the help, I appreciate it. I'm quite new to this engine internal work, but I've done a lot of research and reading, all the stuff you're saying makes sense. I've done all my own work on my ST205 for the last 7 years, so most jobs I have covered, however internals are quite new still as I was too scared to look before :D
I've done engine changes, yes several, and clutch. What a job that is haha!!


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PostPosted: Mon Aug 11, 2014 10:08 pm 
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The small marking on No.1 looks a bit like oil film failure and some of the white metal picked up on the crank, difficult to tell from a 2D photo though. The remainder looks like contaminated oil. Has the engine been run low oil at all ?

You can get an initial idea on crank endfloat by prizing the crank pulley each way. I would guess you could try feeler gauges between thrust washer & crank to measure although you'd normally use a dial gauge on the end of the crank. From memory the clearance should be pretty small. The BGB does give details. The greater noise when at an angle I think is far more likely gravity working on the crank than oil being at an angle in the sump.

The oil flow is from a main gallery via drillings to each main bearing through a hole in the shell. The mani bearing upper shells have a groove to allow oil flow to the holes in the crank that feed the big end bearings. Each main bearing journal has 2 drillings 180 degrees apart which join and feed the big end, this means 1 hole is always in the groove in the main bearing shell containing pressurised oil. I presume you fitted the main bearing shells so that the grooves were in the block half ? I seem to remember you can't fit them wrong but not 100%.
As far as I can see, the only oil feed to the little end bearings is from a small hole with a funnel shape in the top of the conrod. This will rely on oil from the squirters plus gravity. The drilling in the conrod from the big end looks like it just exits upwards and sideways to spray the bore, seems a bit strange considering the high capacity sprays available. Maybe the drillings are just historic.

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PostPosted: Mon Aug 11, 2014 10:25 pm 
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p.s. just checked, endfloat should be 0.02 - 0.22mm max 0.3mm

p104 https://dl.dropboxusercontent.com/u/831 ... rm398e.pdf

For procedures p145 on of this one. P148 for crank endfloat.

https://dl.dropboxusercontent.com/u/831 ... rm396e.pdf

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PostPosted: Mon Aug 11, 2014 10:53 pm 
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I think the conrod drillings probably provide bore and little end lube on the ge engine which is sans squirters


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PostPosted: Tue Aug 12, 2014 7:55 pm 
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Just got the thrust washers out.

They measure around 2.43MM or less... sometimes 2.44MM and I've seen upto 2.47MM I'm not sure how accurate my calipers are. They are digital draper expert ones that I've borrowed from someone.

Either way the limit for standard thrust washer size according to the manual is: 2.440 - 2.490mm

They do look worn on the surface too. Could this be mu problem do you think? Worn thrust washers allowing too much end play on the crank? Which in turn would allow the rod caps to hit against the web?
Is that feasible or am I stretching??


Main bearing number 1 is perfectly fine, in fact it doesn't even look worn. Measured within standard spec for the bearing size...
All the oil holes I can see look perfectly clean, gleaming inside, not a sign of any gunk....
No idea why con rod bearing 1 & 2 have that weird patch on the top half.... is it normal for the top bearing half to take more wear than the bottom half, is it exposed to more pressure/force?

I'm thinking I'll get 4 conrod bearings and a thrust washer set and then reassemble.
I can't find anything out of spec bearing terms, mains or rods, all the oil clearances are well within specification. Thrust washers seem to be the only thing close or out of spec.


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PostPosted: Tue Aug 12, 2014 10:44 pm 
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Thinking about it, I'm not convinced we're not getting over focussed on markings on the bearing shells. If the clearance is within tolerance, then the noise shouldn't be big end knock. I've run with big end clearance at the upper end and even slightly beyond and no knock even on first start up before the oil gets round.

Try and measure crank endfloat you can use the digital caliper to measure distance betwwen a point on crank and a point on block with crank levered in each direction.
Using the same method, measure the side to side play of the big ends (as shown in the 202 link I posted above).
Also, use the calipers to measure the diameter of each big end journal in line with crank (vertical with journal at bottom) and at 90 degrees (vertical with the crank set to mid stroke). You can alternatively measure clearance with plastigauge with the crank in the mid-stroke position (all 4 pistons equal height) - assuming your original measurements were taken with crank at bottom of stroke.

Back on the shells mystery, I'm thinking it can't be contaminated oil or the rest of the shells would be showing the same. I'm begining to think it may be oil film failure on the power stroke on those 2 cylinders, maybe due to detonation.
Have you also checked that that the main bearing shells with channels in the middle were installed in the block side on all journals ? (shown in RM396e linked above p165)

Also, can you post photos of the original bearing shells. Did you ever plastigauge these ?

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Last edited by Nibbles on Tue Aug 12, 2014 11:05 pm, edited 1 time in total.

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PostPosted: Tue Aug 12, 2014 11:01 pm 
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p.s. Some other useful reading matter.

http://www.wilmink.nl/Clevite/Clevite_l ... h_info.pdf
http://www.nb-cofrisa.com/docs/web_fallos_ing.PDF

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