15 replies to this topic

[Gunpilot]

During a DE event in my 1996 Miata, my motor started to make a knocking noise. The car remained drivable and I took it off track and onto the trailer. I cut open the filter and found no large chunks of metal to indicare a bearing failure. After much research I figured it was a collapsed lifter. I opened the motor and found that all of my lifters were bad (nice and squishy). I ordered a set from partsdinosaur.com and just finished the install. I cranked the motor back up and the noise was still there!!! Very frustrated now. Attached is a video with the noise. Any suggestions. Could it just be timing, a valve, or is it for sure a bearing gone bad?

[Jim Drago]

That does not sound like a lifter to me.. I think you have a rod bearing failure. Sorry
Jim

[Weekend Warrior]

Sounds like a rod bearing to me as well.... Quit running it and tear it down before you break the rod and push it through the block.

[steveracer]

+1 for the death rattle.

[Tom Hampton]

Yeah, that's ugly sounding.

[Colby Scott]

Definatly not a lifter, I agree with rod bearing

[iambhooper]

agreed, it sound's like a rod bearing.

[Gunpilot]

I was really planning on making a local event at the end of the month. Don't have time to pull motor and do a full tear down. Looking at finding a local used motor in the Houston area or doing a quick fix.

Anyone here ever re-bearing a Miata from the oil pan? No so bad on a Chevy 350, but don't know if this little 1.8 can be done in a similar fashion?

Thanks

[steveracer]

You can't get the pan off without pulling the motor or dropping the sub-frame.

Also, if it spun a bearing, the crank will be scored and require machining, you can't just put a bearing in it and expect it to live.

[Jim Drago]

You can't get the pan off without pulling the motor or dropping the sub-frame.

Also, if it spun a bearing, the crank will be scored and require machining, you can't just put a bearing in it and expect it to live.

If you just r bearing without complete disassembly and through cleaning, it will not make one session. Don't ask me how I know Throw the oil cooler away, YOU CAN NOT CLEAN, if you use, you will be doing this again.
Jim

[Jim Drago]

I have a good engine for you $650, can have in Houston tomorrow. !34k
$125 on shipping
Jim

[dstevens]

I was really planning on making a local event at the end of the month. Don't have time to pull motor and do a full tear down. Looking at finding a local used motor in the Houston area or doing a quick fix.

Anyone here ever re-bearing a Miata from the oil pan? No so bad on a Chevy 350, but don't know if this little 1.8 can be done in a similar fashion?

You're going to have to do an r&r if you put Jim's crate (or any long block). Even if you do drop the sub frame and try to do it in frame there is a pretty good chance of it ending badly. A quicdk fix could grenade the block pretty easily. You'll need at a minimum new bearings and crank machining. And it's a good idea to check your main bearings as a whole, pins and rod bolts, at least in the cylinder that spun. To do it right you'd want to tank it to make sure you get any nasty bits out. If you are time crunched get a known good long block. If I were swapping I'd do either one I could hear run (but then that's another removal) or Jim's.

[Gunpilot]

I just finally came to the realization I would not make my event (in this car), and that a quick fix would ultimately lead to worse problems. I ordered a rebuild kit to include rod, thurst, and main bearings, pistons, rings, and all gaskets and seals. When I get the time I will pull and completely dissasemble. The block will get dipped, crank checked, and head decked. I have a machine shop linned up. Hopefully the process goes smoothly and I have a practically new motor when I am done.

I figured I would have to do the same for any engine I get used to insure it would last also.

From comments it appears I should look into a new oil cooler? This is something I have been wanting to do for my first time, so I am kinda looking forward to it.

Thanks for all the help.

[dstevens]

You won't regret rebuilding the short block. With that and a head from a known builder and a bit of dyno tuning and you'll be well on the way to a strong motor.

[Jim Drago]

I just finally came to the realization I would not make my event (in this car), and that a quick fix would ultimately lead to worse problems. I ordered a rebuild kit to include rod, thurst, and main bearings, pistons, rings, and all gaskets and seals. When I get the time I will pull and completely dissasemble. The block will get dipped, crank checked, and head decked. I have a machine shop linned up. Hopefully the process goes smoothly and I have a practically new motor when I am done.

I figured I would have to do the same for any engine I get used to insure it would last also.

From comments it appears I should look into a new oil cooler? This is something I have been wanting to do for my first time, so I am kinda looking forward to it.

Thanks for all the help.

There is a huge difference in machine shops... Don't go the cheap route, it isn't worth it. Make sure the bores are round within .0002, you really need a torque plate to do a good job. Use the specs in the book for bearing tolerances and you will be fine. Hand the shop the rules on the head, a good machine shop can do it easily and accurately.

Good luck
Jim

[dstevens]

We're lucky we have a couple of places in town that are pretty good, both building race engines. One guy does mostly imports as his base biz while the others guys do mostly circle track and drag builds and lots of taxi rebuilds.

What do you guys do when the bores get too big? Since we can't oversize do you sleeve them or do you just get another donor block?