Engine Failures

#1

Over the past year I have had 3 engine failures and I’m looking for some opinions about possible causes.

Engine 1 - Original Engine ~225,00 Miles - Installed a Metal Windage Tray, Valvoline VR1 20W-50 - Lasted 2 Weekends - Bearing Failure

Engine 2 - Used Engine ~185,000 Miles - Installed a Teflon Crank Scrapper, Mobil Synthetic 15W-50 - Last 1 Session - Bearing Failure

Engine 3 - Used Engine ~160,00 Miles - Installed a Teflon Crank Scrapper, Pennzoil 20W-50 - Lasted 1 Day - Bearing Failure

I’ve never ran a 1/2 quart high, but I’ve always ran full. I’m not buying another used engine; I’m going to have someone rebuild one. I’m debating weither or not installing a Teflon crank scrapper on the rebuilt engine.

I’m not driving these engines hard, especially the last 2. I shift at 5,000-5,500 and go into 5th gear often. I also didn’t miss any shifts on the last 2 engines.

I’m just looking for some opinions/advice as to what oil levels, types of oil, and how many people are using crank scrappers successfully.

#2

I run the teflon crank scraper. I did not install it but my mechanic said it took quite a while to get it just right with out hitting. I also changed the oil & filter after running the engine for a bit immediately after the install. This is all on my original 140,000 mile motor. It has been running good for almost 2 seasons now. I just had it redyno’d at Mid Ohio last race weekend and it puts out about 152/152, not great but pretty good for the age of the motor. I hope you have better luck in the future.

#3

Sorry to hear about your misfortunes!

Since you have a consistent failure point on all 3, it makes me wonder what components outside the engine are the same that might be contributing to the bearing failure.

I’m exposing my ignorance, but is there anything from the flywheel back that you have used on all 3 engines that may be causing the failure? I wonder if the assumed oil starvation is not the cause…

In the event it is, I know some Miata engine builders are really specific about using Mazda’s OEM oil filters. Are 325s sensitive to the type of oil filter?

Steve D.

#4

Are you using the same head everytime?

#5

First, don’t put Teflon inside your engine!! Second, always run 1 quart high. The slanted engine will run the pickup dry in left hand corners like 5 at RA and 3 at RR. A larger pan will help, but most importantly, a properly baffled pan will alleviate the problem. We need to Canton to build an e30 pan…I would think if we could purchase 10-20 pans, the cost would be reasonable.

BTW, I modified a steel pan to hold 7 quarts with all sorts of baffles and shelves and that seems to fix the oil starvation problem for me. Now, if I could just keep it from leaking:blush: Chuck

#6

No, each engine failure is with a new head.

I used the same parts from the engine back on each failure (flywheel, clutch, etc). I really don’t know how this could cause bearing failure, but I’m not an expert either.

I’m using Mann oil filters.