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Another nasty noise thread... (shit!)-please help - Update 27.04.09
I think I have to get used to get the engine rebuild...
I drove around a bit today, also at the German Autobahn, as I experienced some slight bogging at ~6.000 rpm (5th gear) - boost ~10PSI. Had a look at the gauges, watertemp was high but O.K. - I think ~95°C-100°C (200°F-212°F), Oilpressure was good ~4bar, but Oiltemp was really high at *125°C (*257°F). I slowed down immediatly and everything seemed fine. But as I got off the Autobahn and could hear a bit better, I heard a faint knocking sound. Car is driving O.K. Here is a video of the sound: I think it's a bend rod?! Any other thoughts? Next steps? Thanks |
Vid not working
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The last motor I heard tap like that under neutral throttle was Emilio's old 01/99 junkyard combo. It was a wrist pin knock and the motor let go shortly after that.
It's time for a motor build. |
I make myself already common with this thought - well as this seems inevitable - should I go with an 1,8 Motor now? (As this is a 1,6 NB which never made it to the US)
I don't know if the rods and pistons of the 1,6 NA fit the NB motor (I will have to ask this at the German board I suppose)... What would you say - go 1,6 with good rods and pistons or just sap in a used stock 1,8 and go from there? (I am going to run only up to 9-10 PSI anyway.) Greets |
btw- neither of those temps are high- as in damaging the engine high.
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Yes I know, actualy I had a look at my log and the watertemp was at 84°C max which is rather cold (but it's also only ~20°C outside).
When I had my turbo-kit installed a long time ago they fucked up the oil-return, metall shavings were in the oil-sump and held the oil relieve valve open. No oil pressure = bearings went to hell. They rebuild the engine with a new head and I suppose they did something not entirely correct which was a kind of weak point. Now - go 1,6 with forged rods and pistons or go 1,8. (I like the fast spool-up of my 1,6 with fidanza flywheel - so maybe I should rebuild the 1,6) Hopefully the 1,6 90-93 pistons (wiseco or such ) fit. If I see this correctly rods should be the same for the 1,8 and 1,6...?! |
go with the cheapo CAT/Probe rods. They're working for everyone here, and I'm about to break 300whp with them.
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Where do I find them?
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Originally Posted by Zaphod
(Post 392994)
Where do I find them?
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Yeah, similiar to my noise. Thinking mine is wristpin knock also. Looking into a rebuild and I've alrdy got my shopping list on belfab ready lol.
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ummm, I'm going to say exhaust leak :dunno:
haha I keed I keed. that sucks though. but you can now build a killer short block. |
Is this sound happening at idle also or just when the car reaches certain rpm or louder under load?
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Originally Posted by flier129
(Post 393770)
Is this sound happening at idle also or just when the car reaches certain rpm or louder under load?
Stephanie |
The sound is at idle and getting louder, when I rev the engine.
I think, I will have the engine getting opened this week. Mazda had a problem with weak valves at the 1,6 NB-head over here up to a certain VIN. My car is within this range but my valves are already swapped, but could something like this be an option? Other wise I think about getting the belfab pistons and rods-combo. I know the rods seem to be quite reasonable, any thoughts on the pistons? Greets |
My car is making a similar noise (after beating on it) because my water pump bearing is shot. Take off the accessory belt and see if the noise goes away.
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I just made another vid as I brought my car to the garage:
The noise is very loud at cold start, seems to get better when warmed up. Sometimes at idle it's nearly gone, but when I rev the engine it's getting louder. It is completly gone when I pull off the gas. Sound comes from the back upper part of the engine. I switched to our NA Miata just after that and one of the hydraulic lifters was a little stuck, the sound was nearly similar. Could it be, that one of the valves is damaged? The car seems to run flawless otherwise. |
I don't know why you guys keep trying to fool yourself into thinking that kind of noise is something other than real bad news. if it was valves or related, it would be more of a chatter. what you have there; son, is knock. it could be rod( big or little end), or it could be piston. either way quit driving it, and ffs quit making videos of you reving it. you are doing nothing but making the situation worse and potentialy ruining a crank that might be savable.
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Well, I think I made clear that I already made myself comfortable with a engine rebuild. But as I haven't got an engine hoist, I needed to go to an garage. So this was the last time the engine was running - and moreover this was the last video... I just made this video because the sound was a little changed, when I brought the car to the garage. (I didn't especially make a new video to annoy you ;) )
Today I will know if it has got something to do with the valves - other wise I already sourced a used 1,6NB engine with 68.000km (not mls). Which I will swap in and do an engine rebuild with all necessary new and improved components next winter. That is the best soultion to get me back on the road soon. Greets |
Update...
... I see a engine rebuild in the near future...
Valve clearances were all within the specifiations. The whole valvetrain itself looks flawless. Only thing we found was this little plastic part lying within the valve cover - as it is plastic - it certainly doesn't make such a nasty noise... So - looks like an engine rebuild now. I am a bit undecided whether I should buy the used 1,6 engine and do the engine rebuild next winter or if I do the rebuild now with my actual engine... |
plastic part? is that the remains of your PCV valve?
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No, it looks like a little wheel from a tool or something...
Car is at the garage - hopefully I will know more soon. |
O.K. first news about my engine - the mechanic just told me its a damage on cylinders 2 and 4. (I don't know the english word for Kolbenkipper - piston is moving to much to the sides and damaging the sides of the cylinder walls)
Engine is going to the rebuilder on Monday to give me some numbers about overbore. |
Its not what you would call normal wear. What are your AFRs like? Could that be caused by excessive bore wash from weeping injectors?
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Hi,
the AFRs were within reasonable values. Espacially when this happend (~6k RPM, 5th gear full boost ~10-11PSI) there were ~12.0 AFR nearly flat. Edit: That is a screenshot of when I believe that happened. I had some slight bogging just up top. I suppose this was when the piston hit the wall. https://www.miataturbo.net/forum/att...1&d=1240839123 Greets |
Looking at the data log it looks like you were under a lot of load for at least 30 seconds. Being a noob I don't know what the factory piston to wall clearance is, but I would venture to guess the excess heat by such long high load runs caused the piston to expand into the cylinder walls. #2 must have had less tolerance than 1 and 3, and we all know that #4 gets hot anyways. This being the case I would suggest having the block bored ever so slightly larger than the factory tolerances to alleviate this problem in the future.
And that bog would have been the pistons digging into the cylinder walls. |
Thats what I am thinking... BUT being on the German Autobahn this isn't an awful long time. So I will have a word with the engine shop, once my ingrediences are in...
Greets |
Today I might have found a hint, why the engine was damaged.
I was wrong with my inital thought it couldn't have come from the MS - because indeed we have a batch injection of Nr. 1&3 and Nr. 2&4 Today a Release Candidate for the new NS2extra firmware came out with a correction of two bugs from the last beta versions: * 2) Fixed a problem with the "Incorporate AFR" feature that could cause the second injector channel to not get the AFR incorporated into the equation, causing pw1 and pw2 to be different. (Jean found and fixed this in the 3.0 alphas, I backported it). * I got 2 screenshot of logs old (version 2.0.1) vs. last beta (version 2.1.0) old: PW is nearly identical to PW2 http://www.ingenieure-reichel.de/upl...ld/log_alt.jpg new: PW is mostly ~0.2 sometimes a up to 2.0 higher than PW2 http://www.ingenieure-reichel.de/upl...ld/log_neu.jpg I get the feeling this could have caused a overheating of Nr. 2&4. What do you think? Greets |
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