Wcrawford

This is my first engine build, and it seems something is going wrong.

I was following FM's engine break-in procedure, i set the rings with break-in oil, then changed it. Then i ran break-in oil for 50 miles, then changed it to 10w30 dinosaur oil. I did zero boost for the first 50 miles, then set it up to be able to run up to about 5 psi. Now i have a knocking noise on quick free revving or under low load driving. It doesn't happen when cold, and it doesn't happen at high load. It only seems to happen around 2500-3500 rpm. Oil pressure is good, around 31-33psi at idle when hot, jumps to 55-60 by 2500-3000rpm. 85-90psi cold.

I really don't want to pull the engine and tear it down again, but i also don't want to lose my expensive build.

The engine: 2000 BP4W had a spun bearing, but machinist said the crank and block were fine. I had it bored out to 84mm, but don't remember the tolerance the machinist recommended. He did slightly more than the piston manufacturer sheet, but he was highly recommended and this was my first build, so i went with it.

The pistons are Wiseco 8.8:1 on Manley rods with ACL race bearings, stock size, per machinist. I didn't recheck clearances. Headgasket is cometic 0.040". Valves are supertech stock size, but intakes are backcut. Springs are supertech "light double" with titanium retainers. Injectors are ID1050X on a FM rail set up with dual feed with return line. Fuel labs FPR on return line set at 44psi when engine is off. Spark is flowforce LS2 COP with the extended reach NGK 7s gapped to 0.030. ECU is SpeedyEFI with a tune built off one that was running my 1.6 for 2 years. My O2 sensor is currently acting weird, but i turned off all correction, so in running pure open loop. The engine has been running rich and I'm slowly leaning it out, since i thought it would be safer.

I don't know if anything else is relevant, but I should be able to answer whatever you could need about the build. I'll try to upload a video.

Wcrawford

Hopefully this works:

curly

iTrader: (25)

If you run an oil cooler, factory or aftermarket, and didn’t replace it after the spun bearing, you just ruined your new bearings. That being said, the sound in the video is very quick, there’s a chance it’s a solenoid like VICS or a loose bolt that rattled at a certain RPM. But you could confirm with cutting the filter open, or putting extremely heavy weight oil in and see if it goes away. If it does, it’s probably bearings. The filter is more telling than the noise though. Because regardless of the noise, if it’s full of metal, the bearings are shot.

Wcrawford

Pretty much everything is new. This engine has never been in this car. No oil cooler, but i do have an oil filter relocation kit that was used, but fully cleaned and then run on my 1.6 for an entire autocross season.

The VICS is a good guess. I have it plumbed to a solenoid, but i don't have the solenoid wired. I don't know if it's closed or open. I'll wire the actuator so it can't flap.

I'll also cut open the oil filter and see if there's doom glitter.

LeoNA

I would cut the filter and drop the oil for inspection. If there is metal it needs to come apart. If there is no metal increase the oil to 5,10-40 or better yet 15,20-50. It doesn’t need to be synthetic for testing. I would check the valve train and head straightness. Pull the VC, put a straight edge across the rails and in the center across the plug bosses. If it is a rod bearing again you have to do a bit of soul searching and maybe a better machine shop.

Wcrawford

I'll cut open the oil filter tonight after i get the grub to sleep.

For the record, i bought the engine mostly disassembled after the previous owner had the rod knock. I have no idea what they did to it.

But i may have found a possible source. The timing belt tensioner seemed to stick a bit and it has some play. A LOT more play than the idler one. They were new, but i think i remember it feeling a little odd when i put it in. It definitely seemed like it's been really hot. Hopefully that's it. But I'm still checking the oil filter.

Wcrawford

Well, now the question is how much glitter is too much. There's no real shavings, just a few tiny speckles. None in the bottom of the oil filter (and it sits with the open end up), but rubbing the filter on a shop towel gets this. Tiny gold flakes. The oil isn't discolored, that's just dark because it's dark behind it.



So, is this a reasonable amount for a brand new engine freshly machined and in the first 100 miles of break-in, or am i screwed?

Also, if i do just put 15w40 in it and run it for a while, what will it destroy that i don't already have to buy, assuming i don't let it get so bad it ventilates my block?

curly

iTrader: (25)

If you put a thicker oil in it and the noise goes away, that means you need to tear the engine down, as the wear will continue, and eventually the noise will come back. It's difficult to diagnosis with that photo though, but anything gold colored is usually an inner layer of a bearing. At the very least the crank should be replaced with the bearings, again with any and all oil coolers, like the stock donut oil cooler behind the filter. If you continue to run it, it can also damage rods.

For better results, buy a filter cutter like this one:

I always cut them open on top of a clean shop rag (actually a stack of about 5 of them), and by the time the oil soaks in, you're only left with what was in the oil, the rag itself acting like a bit of a filter. Place the filter material upright, and it'll drain so it's easier to read as well.

Wcrawford

I totally forgot about that stock oil cooler. Well ****, that might have been it.

I cut open the oil filter on clean rags in a tray as you say, but i ended up having to use a chisel, so it didn't go as cleanly as i like, and the sparkles weren't showing up on the camera on the white paper towels i used initially.

Anyway, i looked up what the bearings were made of and the inner surface is a lead-tin-copper alloy that is gold in color and not magnetic, so that's exactly where this stuff is from.

You think i need to replace the crank? Is there some aftermarket crank that's better, or even a source for new cranks? The only thing i can find is pretty much ebay used ones and "enginetech" from autozone. Is it likely that I'll need to replace the rods?

curly

iTrader: (25)

Your rods should be fine if they don’t seize. If the big end is discolored when removed, I wouldn’t reuse it. The more you run it with bad bearings, the more friction/heat is creates, the more you risk damaging the rods. The crank can be reground, and although I’ve done it successfully in the past, I don’t recommend it. Find Miata specific used part sellers, don’t use auto parts cranks.

Wcrawford

I'm not finding a source for good cranks. I found one crank from Treasure coast, but it's reground pretty far off stock, and there's a few on ebay with visible scratches.

Do you know of any good sources?

LeoNA

Did you drop the oil and look at it? Make a long cuetip and swab the bottom of the pan. Scrape the oil on the bottom to see what it holds. The filters don’t catch everything because the bypass is only approximately 10dpsi. With such low use I doubt you wore through a race bearing. Especially if the engine turned over by hand when it was built.

Cranks are hard to find. I have be wondering for awhile if the later cranks with the larger thrust will work in an early block with the small bearing. Maybe someone knows and that might make it less difficult to find a crank if needed. If your crank is standard and will clean at -.25mm I would have it ground.

Wcrawford

I didn't drain the oil pan yet.

I took a look in better light and there is a bit of glitter in the oil in the bottom of the oil filter, but not a lot, and the largest piece i could see is about the size of the smallest visible mark you can make with a freshly sharpened pencil. It was difficult to take pictures of them, because they're so small.

I called around and found sourcing a crank is going to be very difficult, so I'm going to have to either clean up this one or buy another one that's scratched and clean that one up. I'm hoping it just needs a polish.

A few people aren't convinced it's rod knock, so we're going to look at it this weekend. I can drop the oil and swab the pan then or maybe before and fill it with 15w40. Maybe I'm wrong? I hope I'm wrong.

curly

iTrader: (25)

If it spun a bearing, and you rebuilt it with race bearings and didn’t replace the donut cooler, I’m sorry but there’s a big probability it damaged your bearings. Race bearings are used WAY too frequently IMO, many owners don’t realize the amount of filter changes they’ll have to do to prevent premature wear. They’re amazing in perfect conditions, and that’s about it.

Wcrawford

Oh, and i read that the later cranks are still the same, but the difference is the block for the ticket thrust bearing. Not sure if that's correct.

Wcrawford

It's on the third oil filter at 65 miles.


Are these tiny gold flakes doom for my bearings? They're difficult to take a picture of. They're very small and there's not a lot of them.

I didn't replace the donut cooler, though. What bearings do you recommend for a turbo build looking for north of 300hp?

curly

iTrader: (25)

Stock. That’s what I’m running at 330hp, and have never seen better oil analysis results.

LeoNA

I would run Mazda main bearings with the harder race bearings on the rods. Mainly because of the better quality of the OE bearings in regard to sizing not so much the embeddability. I'm in the process of testing filters for improved capacity and higher bypass pressures. Specification wise the HP 17 Fram looks to be an option.

Wcrawford

For anyone curious, it absolutely was rod knock. I don't know why, but #1 was worn pretty badly. The other 3 were scuffed, but not really doing anything bad. I think it pretty much must have been essentially a dry start. It took a bit of cranking to get oil pressure, but it didn't actually run without oil pressure.



I'm not sure if i can polish that crank to good enough or not.

LeoNA

Have you checked the mains and oil pump?