evotr

Hello All,

I wanted to share my experience and get your feedback on this. I found out after a quick search (which I should have done before buying BE pump and ACL bearings) that there have been similar cases before.

After an MS injector mosfet failure, 500 iq repair job and then failure to hydrolock, I finally got the engine rebuild. However, after around 800-1000 km break in without issues, noises were heard on the dyno and engine was removed again. Turns out 4th (closest to firewall) rod bearings turned. My shop said that others were also damaged, so it would have been a disaster if the sound was not noticed. (a worse disaster anyhow). Additionally oil pressure never dropped. (This is a 1990 NA with long nose so true oil pressure gauge)

We are now in the process of replacing damaged parts. Since this is mostly US forum, I could not find info on compatible crankshafts but for our Euro friends, mazda lantis 1.6 crank seems to be exact copy of long nose NA6. This engine, we have a lot locally. Otherwise I was screwed since there is no crank for sale online and transporting a crank internationally is really not pleasant.

-Did anyone have any experience like this before and figure out exact reason as to why it happened? (especially besides stuck open oil pressure relief valve)
-We are checking the pressure relief valve in detail. So far it does not seem to be stuck open.
-Should I go directly for OEM (genuine mazda) bearings or is there an actually tried and tested brand that forum agrees on?
-Power expectation is 200+ at the crank, basically limit of the oem gearbox. (TD04 with low comp pistons, shitty fuel)
-Manley Rods, Wiseco Pistons, BE pump (vvti compatible, basically top of the line) ACL Race bearing set complete.
-Extra: It turns out, local Honda scene also had a lot of scare stories with ACL bearings so they stopped using them.

Anyhow on with the photos:





Update: Appearently 1.8 323 engines have the exact same crank. My shop said that, after inspecting cranks from salvaged engines, there are 2 types for both engines, either short nose or long nose (based on salvage yards here of course). Once that was cleared finding good quality japan made oem spec beraings was not an issue. Car is back on road for another round of break in but now clutchmasters clutch decided to quit. Clutch disc is gone in 1 break in (800 km), pressure plate has small broken parts became unusable. Clutch is slipping without boost and under soft break in driving.

cnano8

iTrader: (1)

What bearing clearances were you running?
On the crank you can just have it turned and use the correct sized bearing to match. Probably cheaper than having to source a crank overseas and pay for international shipping since its a heavy ****.

evotr

Bearings were standard sized but I do not know the exact clearance for the installation. Crank is beyond turning unfortunately, as the damage is very deep. There is a very small chance that machine shop (honing and refurbishing is a separate line of work here) might have made a mistake but they control everything while honing the block. Hopefully Lantis crank will be a %100 match.

curly

iTrader: (25)

I had a similar issue, blamed it on running race bearings with unground 140k bearing surfaces. I used oversized bearings, ground down the crank appropriately, so far so good. But if your oil pressure never drops, the engine was properly assembled without any foreign contaminants, and assembly lube was properly used everywhere, then poor bearing surfaces are to blame IMO.

RACE bearings can take a LOT of abuse, their biggest weakness by far is surface finish of the crank.

STREET bearings can still take some abuse, especially at the lower limits we push these engines, and can stand up to some surface imperfections.

evotr

Thanks, still waiting for the shop to find time for a proper inspection. You may be right, there was no issue for the break in period and then it just degraded very fast with increased power levels on dyno. I am pretty sure that debris is not an issue but not sure about crank imperfections.

Real question is, are ACL bearings (or other "better performance" ones) really better than OEM or is it really a matter of price point, since they are considerably cheaper - less than half price for a full set.?

der_vierte

King XP bearings are good and somewhat cheap. OEM or equivalent should also be just fine for your power levels on the street.

I could help you out with a crank from Germany, but "cheap" EU shipping is only available up to Bulgaria :/ Can't Turkey and the EU just get along? I don't understand the whole world tbh.

Lazeum

Like it could very be a quality issue on parts, I would suspect other problems first.

Looking at your parts, it looks like wear is mainly on the inside of the bearings and caps. It is not on the whole thickness of the bearings - that would have meant improper bearing clearance for instance, major imbalance somewhere or oil starvation. Knowing 4th cylinder is the worst, I would have looked at clutch & flywheel.
Bearing "quality" would also show wear on the whole thickness of bearings.

This leads me to believe something was wrong inside the oil. Some debris could have traveled thru oil destroying bearings - and other components to be defined (cams?).
Taking this into consideration, debris could come from turbo, oil pump or head/cam. There's filter in between oil pan/pump and engine internals, I would inspect filter first and check inside by cutting it. That may give you some clues about what happened.

[edit]: looking again at the pictures, not sure if my comment is really valid.
I'm wondering how bearings could turn with indentation, that should avoid such issue to happen.

evotr

Thanks all for chiming in. As a sidenote, during the first oil change (end of break-in), oil filter was clean and there was no excessive/alarming metal debris.

It turns our we can grind the crank 0.25, as Curly suggested. My mechanic is worried about durability if we grind. He still did not check the replacement crank from Lantis, dimensions seem ok but from what I gather, NA cranks are lightened so we need to check the weight too. I am losing confidence in replacement and thinking of oversizing instead.

Do you remember which size you went for and which bearings you used?

curly

iTrader: (25)

I was using STD ACL, went with the standard oversize, which is .020 or .5mm. Once ground, I couldn't get the ACLs, so I got King race bearings. so far so good, I need to send an analysis out to make sure I'm in the clear.

evotr

d
Thanks for the reply, I think I will try King. Although it seems that both companies only supply race bearings now, hard to find "street" spec, which should be "error" friendly. Funny enough, Mazda's oversized bearings are significantly cheaper than their stock sized ones, no idea why. Do you mean check the current wear on your bearings?

evotr

Update: Appearently 1.8 323 engines have the exact same crank. My shop said that, after inspecting cranks from salvaged engines, there are 2 types for both engines, either short nose or long nose (based on salvage yards here of course). Once that was cleared finding good quality japan made oem spec beraings was not an issue. Car is back on road for another round of break in but now clutchmasters clutch decided to quit. Clutch disc is gone in 1 break in (800 km), pressure plate has small broken parts became unusable. Clutch is slipping without boost and under soft break in driving.