Zaphod

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

Laur3ns

Vid not working

Savington

iTrader: (31)

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.

Zaphod

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

m2cupcar

iTrader: (5)

btw- neither of those temps are high- as in damaging the engine high.

Zaphod

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...?!

hustler

iTrader: (6)

go with the cheapo CAT/Probe rods. They're working for everyone here, and I'm about to break 300whp with them.

Zaphod

Where do I find them?

hustler

iTrader: (6)

BELFAB RACING PRODUCTS

flier129

iTrader: (7)

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.

dynokiller90

ummm, I'm going to say exhaust leak

haha I keed I keed. that sucks though. but you can now build a killer short block.

flier129

iTrader: (7)

Is this sound happening at idle also or just when the car reaches certain rpm or louder under load?

Stephanie Turner

Agreed, important need to know info. But my first thought is that is does not sound like the bent rods I have heard before.
Stephanie

Zaphod

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

Duckie_uk

iTrader: (1)

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.

Zaphod

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.

dynokiller90

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.

Zaphod

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

Zaphod

... 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...

curly

iTrader: (25)

plastic part? is that the remains of your PCV valve?