Symptoms of dying rod/main bearings?

[Tippy]

1987 Carrera 3.2, turbocharged turning to 6750 with ARP rodbolts.

Normally, I am confident on diag. someone else's woes, but I need opinions from those who have been around this type of issue since my emotions/disbelief may be clouding my judgement.

Out of the blue, my 7.5:1 CR turbo 3.4 (based on 3.2) started running warmer than normal. Not hot, but the temps seem to climb at a faster rate. Also, noticed the passenger fender for the oil cooler seemed very warm. Never in 18 years remember it being so warm and I am pretty sure the fan has never worked. Of course that needs to be addressed.

Saw it had ingested a couple of blue shop paper towels through the cooling fan, I thought, aha(!), that is the root cause. Spent a few nights slowly picking out shreds of towels from cylinders, heads, and oil cooler shroud pathway confirmed 100% clear with a borescope and mirrors. Drove it again and no change.

Next, I noticed the oil pressure was lower than normal. Normally, on a super-hot day, stuck in stop and go, or just a long drive on 100F days, the oil pressure may get down to 0.8-0.9 bar. Lately, I am seeing 0.5 and have never seen it that low just in 15-20 minutes of normal driving, no real stop and go with temps in the low 90's.

It feels off. I have driven about 3 times (15-20 minutes tops) since this pattern has occurred.

What really concerned me was after another short drive (the last time I took it out) at idle, I was seeing the needle drop to 0 after about 15 minutes of driving already warm from the previous trip. If I took it just off idle to say 1200-1500, the pressure would go up to 0.5 - 1.0 bar. I know it is common on 3.2's for this to happen, but it never has. Tested ohms to pressure sender and it seems to be in spec with no oil pressure on it/static. Have not confirmed the resistance with pressure.

So, I pulled both oil thermostats and the engine one is opening like 3/8" - 7/16" of an inch, so it's totally fine. The external from the rear fenderwell area is moving like an 1/8" to 3/16" if I had to guess. Much harder to judge since the piston is not in line of site.

Concerns/details:

-Switched from Rotella T6 10W-40 to 10W-50 VR1, no change to heat, just little better pressure

-It seems the motor slows to a stop sooner after shutoff (in milliseconds here, not instantly)

-Have 993SS cams, so the cam chop makes the engine run rougher than stock 3.2 cams, so it is hard to judge "noises" of the low end (no knock or tap, but doesn't sound as smooth as before if that makes sense)

-Reused both sets of bearings since they showed no wear from 1st rebuild (low mileage) and fit tightly still exhibiting "snap" (biggest reason I reused) "refreshing" motor 4 years ago to this day

-Have not found any metallic objects in the internal oil thermostat, oil drain plug, external oil thermostat, or oil pressure sender block/banjo bolt since this started.

Would have ruled this simply as an aging oil pressure sender or gauge common on 3.2's, but coupled with having higher heat than normal, something is amiss.

If these are symptoms of bearings letting go, I want to catch it before I eat the crank, cases, or both.

Thoughts?

TIA for any input! Cory

P.S. - video of it idling since I discovered an issue. Belt removed as I was trying to locate a squeak which turned out to be a telescoping mirror that fell between crank pulley and console:

https://youtube.com/shorts/-v0nHeBtc3s?feature=share

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[safe]

The fender usually gets pretty hot on my car on a hot day.
An oil analysis would reveal abnormal bearing wear. Maybe you shold do an oil change if its gotten really hot or fuel diluted so the viscosity have lowered.

[Tippy]

Originally Posted by safe

The fender usually gets pretty hot on my car on a hot day.
An oil analysis would reveal abnormal bearing wear. Maybe you shold do an oil change if its gotten really hot or fuel diluted so the viscosity have lowered.

Yes, I plan on sending to Blackstone. Agreed.

It has never even gotten to the 3rd hash mark (4th being the red zone), so I am confident I haven't cooked anything.

[Black_Hat]

remove and cut open your oil filter
look for glitter other stuff

[Tippy]

Originally Posted by Black_Hat

remove and cut open your oil filter
look for glitter other stuff

Will do! Amazon FTW to get a cutter today.

I have the "refresh" filter too to cut open saved in a Ziplock bag to inspect. Good idea.

[brighton911]

Before going any deeper, I would verify the oil pressure with a master gauge. Here's hoping there is good pressure and it was just a sender/gauge issue.

[Tippy]

Originally Posted by brighton911

Before going any deeper, I would verify the oil pressure with a master gauge. Here's hoping there is good pressure and it was just a sender/gauge issue.

Yep! I see there is a lot of meat on the oil pressure sender block to tap for a 1/8" NPT.

Will be doing that soon and already have a brand-new Bosch mechanical gauge to test with.

The quicker heating up is just throwing me off......maybe it's in my (custom) tune since I am EFI.

[dannobee]

Retarded ignition timing will make it run hotter.

[Tippy]

Originally Posted by dannobee

Retarded ignition timing will make it run hotter.

You know, I did lower base idle timing to 10 from roughly 15-20. Timing is dynamic with the EFI to maintain RPM, so it fluctuates around target.

I did overlook that.

[snbush67]

A lean mix will run hotter. Check the AFR’s at all ranges. Check for equal exhaust port temperatures at idle and at varying engine speed intervals.

[Tippy]

Originally Posted by snbush67

A lean mix will run hotter. Check the AFR’s at all ranges. Check for equal exhaust port temperatures at idle and at varying engine speed intervals.

I have an AEM WBO2 in the clock hole. Always have one eye on it. Nothing abnormal.