Can I Save the Old Girl?

[67rway]

Oil Seat, etc.

Despite well below freezing temps (quite unusual) here, I've continued work on this issue.

At sastanley's suggestion I've gotten more aggressive with my engine treatments, and have been using Seafoam for upper end treatments, run it through the intake running, and ended with 12 oz in the crankcase. So far #4 still shows 20% lower compression, which I'll remind bumps dramatically when wet. I plan to continue such treatments for awhile longer.

I've also added the Indigo PCV system. It's impossible to distinguish whether it's better or not yet, given the chem soup I've been feeding her... I need to run her hard/hot, and our current weather is not cooperating.

Taking Don's suggestion; I took the oil pressure valve apart and used a 1/8 pipe (combo of parts, actually) to 'dress' the seat. With any luck you'll find a series of pics attached.

First are the valve before, a 180 view of the valve before, and of the seat (via borescope promised in concurrent thread). What I found (sig or not?) was a noticeable ridge on one side the valve face, and a seeming burr on the seat (shiny area).

Next are views of the valve (edit: not possible due to 5 image limit) afterwards showing more even sealing surface, and a matching view of the seat. I suspect the variation in the seat appearance may be due to the valve sitting slightly lower in the seat (gravity effect?).

I'd be interested in hearing from others who have used the pipe/tapping procedure for their results.

[JDK]

using an oil that is designed for a diesel engine in a gasoline engine which obviously has completely different chemical and internal conditions is a mistake.......thats lubrication technology 101 for beginners......i hate to have to say something but i cant in good conscience keep listening to you guys discuss making such a mistake over and over again.......there are other reasons, very many very technical reasons which i will not get into because if anyone actually cared about lubrication they would have learned already for themselves, am i wrong

[67rway]

JDK: While I appreciate all perspectives, your post seems to denigrate many here who have suggestions on how to resolve my issues; oil pressure drops over long periods, and seemingly stuck #4 rings. I’m using several products (MMO, diesel oil, Seafoam) in an attempt to free the rings without disassembly, which probably make many cringe.

I’ll stand by my decision to use diesel oil for its cleaning properties and higher heat tolerance in my old girl despite the difference in shear, ZDDP content, etc. FWIW: There are an abundance of perspectives regarding use of diesel oil in gasoline engines over in Bobistheoilguy.

I’d ask that this thread remain dedicated to resolving my current concerns, and look forward to hearing the perspectives of those interested in educating us about lubrication in a separate thread.

[67rway]

Follow-up

It seems the recommendations above have resolved my cyl 4 sticking ring issue, and she's been running quite well. We sail/race year round so she's had regular use, but it's rarely more than 30 minutes of run time until we start cruising.

So, in order to build confidence that the re-seating of the oil pressure valve corrected the oil pressure drop over time problem, I ran her steady yesterday, mostly in gear. Oil pressure never got alarming, but did drop considerably:
35 lbs at 800 rpm for 10 min
39 lbs at 1800 rpm for 15 min
32 lbs at 1300 rpm in gear in slip for 10 min
29 lbs at 1300 rpm in gear in slip for 15 min
25 lbs at 1300 rpm in gear in slip for 15 min
22 lbs at 1300 rpm in gear in slip for 15 min
18 lbs at 800 rpm (back to neutral)
30 lbs at 1800 rpm (still neutral)
18 lbs at 800 rpm
20 lbs at 1200 rpm in gear in slip

The rate of drop concerns me, leading me to believe it'll continue.

More testing?
Regrind the oil pressure valve seat?
Tear down?

I'd appreciate your thoughts!

[JOHN COOKSON]

It seems the recommendations above have resolved my cyl 4 sticking ring issue, and she's been running quite well. We sail/race year round so she's had regular use, but it's rarely more than 30 minutes of run time until we start cruising.

So, in order to build confidence that the re-seating of the oil pressure valve corrected the oil pressure drop over time problem, I ran her steady yesterday, mostly in gear. Oil pressure never got alarming, but did drop considerably:
35 lbs at 800 rpm for 10 min
39 lbs at 1800 rpm for 15 min
32 lbs at 1300 rpm in gear in slip for 10 min
29 lbs at 1300 rpm in gear in slip for 15 min
25 lbs at 1300 rpm in gear in slip for 15 min
22 lbs at 1300 rpm in gear in slip for 15 min
18 lbs at 800 rpm (back to neutral)
30 lbs at 1800 rpm (still neutral)
18 lbs at 800 rpm
20 lbs at 1200 rpm in gear in slip
The rate of drop concerns me, leading me to believe it'll continue.
I'd appreciate your thoughts!

Since you are asking for thoughts here's mine - for better or worse.
I think you had two problems. Sticking rings in #4 and worn bearings. The sticky rings are unstuck but you still have the worn bearings. See posts 1,21,23. Maybe it's just me but I would confirm the oil pressure readings with a mechanical gauge before I tear down the engine. Post #25.

TRUE GRIT

[joe_db]

Using oil designed for modern clean burning gasoline engines with close tolerances and emission control systems intolerant of zinc in ancient engines with carbs and unsealed crankcases designed back when oil straight out of the ground was more or less what was available is a mistake.
FYI

Shell Rotella T is a line of heavy duty engine lubrication products produced by Royal Dutch Shell. The line includes engine oils, gear oils and coolants. The oil carries both the American Petroleum Institute (API) diesel "C" rating as well as the API gasoline engine "S" rating. Ratings differ based on the oil. Rotella oils like T3 15w-40 meets both the API CJ-4 and SM specifications, and may be used in both gasoline and diesel engines. However, it is formulated specifically for vehicles without catalytic converters, containing phosphorus levels beyond the 600-800ppm range.[1] Therefore, Rotella is not recommended for gasoline vehicles with catalytic converters due to the higher risk of damaging these emission controls.[2] Newer formulations of Rotella T6 however are API SM rated as safe for pre-2011 gasoline vehicles.

using an oil that is designed for a diesel engine in a gasoline engine which obviously has completely different chemical and internal conditions is a mistake.......thats lubrication technology 101 for beginners......i hate to have to say something but i cant in good conscience keep listening to you guys discuss making such a mistake over and over again.......there are other reasons, very many very technical reasons which i will not get into because if anyone actually cared about lubrication they would have learned already for themselves, am i wrong