914-4 2L #3 rod bearing failure Options

[Driver174]

Rod bearings 1,2 & 4 look good, but #3 not so good. This engine has approximately ten race weekends sense it was rebuilt. Has anyone seen this issue?

[Driver174]

Pic of crank journal that doesn't look or feel much different from the other journals except for the marks left from the bearing material.

[Krieger]

I have not taken apart a motor with that little time on it. What does the crank look like?

[flyer86d]

We had the same issue with our modified 1.7. With Sue and I driving it, I would have to rebuild the bottom end mid season running ten to twelve weekend per year. I had two shortblocks. The situation improved when I installed an external oil cooler.

Charlie

[914Sixer]

Are you using steel backed bearings? Aftermarket rods do not have an oil slinger slot that the factory 2.0L ones do.

[ClayPerrine]

I have seen it in a street engine. That is the rod bearing that is farthest from the oil feed to the crank. So it is the first to suffer with oil starvation. It could be anything from an incorrectly installed main bearing restricting the oil flow to the crank, or some debris in the oil feed passage.

Hard to tell what caused it, but I would replace the crank and rods as a precaution.

[stownsen914]

Looks like an aftermarket rod in the pic at top? What rods are you using? Bearings? Any special prep on crank? Any details you can share on usage may help too - hp, RPM, any other significant details. Lots of variables for a race motor that can impact longevity, like oil temp, anything to help with oil starvation in corners (especially of you are running sticky tires).

[ChrisFoley]

Do you have any deep sump or tuna can? Do you maintain the oil level 1/2qt above the full line?
You were lucky. If the bearing material started sticking to the crank it would have seized quickly.

[GregAmy]

:shudder:

That's why I spent the coin for a dry sump system...

[stownsen914]

Listen to what Racer Chris has to say - tons of experience racing the 4's.

[Mark Henry]

Do you have any deep sump or tuna can? Do you maintain the oil level 1/2qt above the full line?
You were lucky. If the bearing material started sticking to the crank it would have seized quickly.

(IMG:style_emoticons/default/agree.gif) looks like an oil control/starvation issue.
Why I like a pro light or some sort of bright idiot light.

[McMark]

I'm late to the party, but I agree with Mark and Chris. Even if your light didn't come on, it looks like starvation to me. You at least need a 'tuna can' sump. If you're serious about racing though, the AccuSump is a great investment specifically avoid situations like this -- and has the added benefit of letting you open the AccuSump reserve tank before cranking the motor and ensure there's a good coating of oil on all the bearings before turning the motor over.

[Driver174]

It has the "tuna can" oil sump and an oil cooler mounted in front trunk. The oil gets quite hot; I think I've seen 240-250 degrees on gage during races.

I asked the original engine builder if I should install an AccuSump, but he claims that he has many of these racing with just tuna can, and never had oiling problems.

[brant]

Is there any way to improve on your oil cooler system?

when we used to race a -4.... We built 3 different cooler exits all using the same motor and same oil cooler....


we dropped the oil temp 10degrees F, each time we improved the cooler air exit

overall 25degree's just by ducting in the least restrictive way possible (through the hood)


sounds a little too hot to me
also if your not doing it.... change your oil after every event
you will notice a longer engine life for the efforts.

brant

[Driver174]

I do believe adding more air exit area from the oil cooler will help with cooling oil. I’d rather not put exit holes through the hood, but wouldn’t mind increasing exit hole size in trunk floor. Was trunk floor exit not effective?

[brant]

I do believe adding more air exit area from the oil cooler will help with cooling oil. I’d rather not put exit holes through the hood, but wouldn’t mind increasing exit hole size in trunk floor. Was trunk floor exit not effective?

trunk floor wasn't a total failure for me

my first cooler duct, had a very short exit that only cut about 8 inches back (from the cooler exit to 8inches rear ward in the trunk floor)

my 2nd exit duct, but back about 10-12 inches into the trunk floor and the improvement showed up on the oil temp gauge.

I then went to the hood soon there after...

but I think a trunk floor exit that cuts back at least a foot into the floor (or more) is still doable.... look at the GT/6 style cooler ducts. they probably cut 12-18inches back, and should work.

[VaccaRabite]

I do believe adding more air exit area from the oil cooler will help with cooling oil. I’d rather not put exit holes through the hood, but wouldn’t mind increasing exit hole size in trunk floor. Was trunk floor exit not effective?

Hot air wants to rise, and the car moving through the air will work to pull air through the top of the trunk lid. Under the car you are pushing the hot air out. Especially if you have any sort of front lip, hot air exiting out the top is going to be more efficient then hot air going out the floor.

For a street car it probably does not matter as much.

Zach

[brant]

I would add that you need air flow under the car to benefit or assist in pulling the hot air out of the cooler when you go down

I used to run the really low rubber lip spoiler on the front
found that by using a less deep front spoiler (LE style) I could improve cooling.

so if your car is really low or has a front splitter... try letting more air run under the car by removing the front spoiler and that can also help with oil cooling.

[stownsen914]

250 is a bit hot. You can easily drop the temp by making sure you have proper ducting to and from the cooler. Make sure the air that enters your duct to the cooler has no where to go except through the cooler. Don't leave gaps or openings - the air will go there instead of through your cooler. Foam weather stripping works well to take up the gaps. Also, the opening in your bumper can be the size of the cooler or even a little smaller. It may be tempting to make it larger, but that won't work - it will just prevent air from going in.

On the air exit, through the hood is a good way. Wheel wells can also work if you don't want to cut the hood. Make sure the exit is at least as large as the cooler. A little larger is better.

Another thing - hopefully you used -10 or -12 oil lines. I've seen -8 used, but that's a bit too small and could restrict oil flow.

[worn]

Do you have any deep sump or tuna can? Do you maintain the oil level 1/2qt above the full line?
You were lucky. If the bearing material started sticking to the crank it would have seized quickly.

In such a situation, what happens to the main bearings at that end? For the bearings to be so galled it almost has to be poor oiling doesn’t it?