Rings vs valves or both

[JPP]

Hi, I have a 218 in a b1b, I am burning oil and am looking to solve this but I use the truck, so I hope to do this in stages. What I am asking is your advice of which I should do first?  Some data. When I start the truck, the oil pressure goes right to 40 psi and holds for a while. Then when the motor gets to temp 160F, the pressure drops to 10 psi.  The truck runs great, 55 mph all day long, 65 mph on highway. If I down shift or step on it, I get a rich plume of oily smoke. I think rings are the real culprit but value all your insights, so your advice is appreciated. Thanks. 

[mechresto]

Blue under hard acceleration is rings, under deceleration is valves.

Your oil pressure says main bearings are worn as is the pump.

[Dave72dt]

Your oil pressure would indicate to me you have worn bearings, possibly the crank also and if that's the case, it needs to come out and get turned, unless these engines tend to run at that pressure when warmed up.  Unfortunately, the plumes of smoke likely mean both rings and valves need attention and the most cost effective process is doing the whole thing at once.  Worn bearings won't solve the plumes. Replacing rings may reduce plumes but you may have worn cylinders, broken ring lands and you're dropping the pan and unbolting con rods to get pistons out before you can measure for cylinder taper  and out of round.  Valves may (probably ) need guides and then seats matched to the guides.  Most of these processes will require the assistance of a professional and at shop rates, you'll save time and money having all necessary work done at one time.

 

You can do some initial inspection yourself by doing a  compression test, leakdown test. then pulling the head and doing a visual of cylinder bores and checking for valve movement in the guides.  You can do engine removal, component removal and basically strip the engine down and do the reassembly and  install.  There are things that need to be marked and noted during teardown and forum members can assist and guide you through that as well as assembly.

[Jomani]

Do you know how many miles are on the engine? Is the low oil pressure something new or has it been getting worse? What are you using for oil?

 

Like Dave said, this is probably not an easy fix and will most likely require removal of the engine. Unlike modern engines, the cylinders in these flatheads are relatively soft and prone to wear. It is very unlikely that you will fix the problem by just replacing rings if it is a high mile engine. A compression test will tell you a lot. First do a dry test, then repeat wet by squirting oil in the cylinder. You should see an increase in pressure when wet. If not, you have something other than rings causing the problem.

[Don Coatney]

Step #1. Do a compression test.

 

 

[55 Fargo]

Step  2 Cylinder Leakdown test, much more conclusive.

Step 3 complete rebuild or find a donor engine, yours is worn out.

Compression tests are very general, and can sometimes not give you the full picture of whats going on.

1 of my engines,compression is down a bit,say 95-100 dry,and the same with a shot of oil, but on a leak down test its very evident that leakage is past the rings.

Engine does not smoke, has good oil pressure,but most likely needs rings,and valves,and then it most likely has cylinder taper and ware, so why waste time, once apart,might as well go all the way.

In my case,she runs well,but is down a bit of pow, will drive her till I have my 265 built...

 

[Don Coatney]

1 hour ago, 55 Fargo said:

Step  2 Cylinder Leakdown test, much more conclusive.

Step 3 complete rebuild or find a donor engine, yours is worn out.

Compression tests are very general, and can sometimes not give you the full picture of whats going on.

1 of my engines,compression is down a bit,say 95-100 dry,and the same with a shot of oil, but on a leak down test its very evident that leakage is past the rings.

Engine does not smoke, has good oil pressure,but most likely needs rings,and valves,and then it most likely has cylinder taper and ware, so why waste time, once apart,might as well go all the way.

In my case,she runs well,but is down a bit of pow, will drive her till I have my 265 built...

 

 

Good point and I agree. I can tell a lot about the general health of an engine by 3 simple tests that do not require any tools.  

 

1) Listen to the starter motor when cranking the engine. If one or more cylinders is low on compression the starter motor will spin faster on the compression stroke of the faulty cylinders. 

 

2) with the engine running remove the oil fill cap and look for blow by in the crankcase. Excessive blow by indicates problems with the piston rings. 

 

3) hold a dollar bill on the tail pipe with the engine running. If the bill is sucked in this indicates a valve problem.

[55 Fargo]

1 hour ago, Don Coatney said:

 

Good point and I agree. I can tell a lot about the general health of an engine by 3 simple tests that do not require any tools.  

 

1) Listen to the starter motor when cranking the engine. If one or more cylinders is low on compression the starter motor will spin faster on the compression stroke of the faulty cylinders. 

 

2) with the engine running remove the oil fill cap and look for blow by in the crankcase. Excessive blow by indicates problems with the piston rings. 

 

3) hold a dollar bill on the tail pipe with the engine running. If the bill is sucked in this indicates a valve problem.

Agree on all 3........ the more in depth Cylinder Leak Down test will confirm all, and with close indication of how much leakage each cylinder may be having...

[Fernando Mendes]

On 12/17/2018 at 2:26 PM, 55 Fargo said:

Step  2 Cylinder Leakdown test, much more conclusive.

Step 3 complete rebuild or find a donor engine, yours is worn out.

Compression tests are very general, and can sometimes not give you the full picture of whats going on.

1 of my engines,compression is down a bit,say 95-100 dry,and the same with a shot of oil, but on a leak down test its very evident that leakage is past the rings.

Engine does not smoke, has good oil pressure,but most likely needs rings,and valves,and then it most likely has cylinder taper and ware, so why waste time, once apart,might as well go all the way.

In my case,she runs well,but is down a bit of pow, will drive her till I have my 265 built...

 

Did you already do this cylinder leakdown test with these equipment?Did not remember who send me these pics.

[55 Fargo]

On 12/20/2018 at 5:05 AM, Fernando Mendes said:

Did you already do this cylinder leakdown test with these equipment?Did not remember who send me these pics.

Twas not I, however did post a pic and/or videos doing a leak down test..

[Fernando Mendes]

On 12/22/2018 at 12:49 PM, 55 Fargo said:

Twas not I, however did post a pic and/or videos doing a leak down test..

Can you send me PM of these pics and videos?