P-15 Engine Help

[JohnTeee]

After a long hiatus from the P15-D24 Forum and my 1947 Plymouth P-15 Special Deluxe Convertible, enough is enough and I want to get it running again.

 

History:

Winter 2011-12 - rebuilt carb, spark plugs, replaced four intake valves with #V1086 and "valves ground" (to my additional shame, I did not record WHICH intake valves they were), Points, Condenser, Fuel Pump, Fuel Filter, fuel tank cleand/lined, under dash/aftermarket water temp gauge installed (original gland broke off sensor cable), head resurfaced and new gasket, 140F Thermostat (don't ask why, I don't recall. Must have seemed like a good idea at the time), intake/exhaust resurfaced

Winter 2014-15-It  Had a 'clutch blowup' and it was out of service for a while. Got clutch back in and wanted to drive it. No exact recall of what I did. I know I mucked about with the distributor and carb float. Had a massive backfire that blew out the side of the muffler. Could not get it to run.

 

I'm not great at troubleshooting engine and so, it has sat. In an effort to get it going again, I was going to take it to my local mechanic who came up 'Old School' and was going to take it on in his 'project bay' when he got done with a truck engine replacement. This excellent gentleman was diagnosed with, and shortly later, died from Pancreatic Cancer. I got in touch with a mechanic who said he could work on the old girl agreed to take it in. Got it in too him and he certainly identified problems; did not return it running. Work he did:

• Replaced battery
• Replaced spark plugs
• Found fuel tank was rusty and fouling the fuel. Lining was flaking off and tank was rusting.
• New fuel tank from Vans Auto installed. (Ironically, they had a better price with shipping on eBay, than their online site)
• Radiator leaking - sent off, along with spare, to local radiator shop to pick the best and fix any leaks
• They had removed the radiator to check timing against the balancer marks
• Ran compression test and found #5 with low compression. Ran 'leak down' and found air leakage into cylinder 6 and carb

 

He knew I had been into the head and valves in the past. In an effort to save me some money, recommended I have it towed back home, pull the head and inspect the head gasket for leaks, or check valves for proper operation, which we agreed it sounded like it could be.

 

Pictures below of what I'm working with. I'll post links, as each is larger than the total size allowed for upload. May have to come back and edit to find a link format that works.

 

I've pulled the head and do not see anything readily apparent with the gasket

 

Nothing readily apparent on my inspection of the block

 

 

Close up of Cylinders 5 & 6

 

 

 

Here is a YouTube video link for a short, head off, crank, showing all valves working.

 

Soooooooo, any thoughts about where I need to concentrate my attention?

New head gasket obviously. Several years before all of this I had put a different head on, I think because it gave me a few more C.I. - it's the type with the bypass hole, which my block does not have. Guess it doesn't make any difference which head gasket goes on, as that hole isn't going anywhere?

Check valve clearances?

 

I really appreciate any ideas. I'm not sure how much

 

 

I'll tackle the rear differntial pinion housing leaking and passenger door latching on down the road . . . <grin>

Edited November 16, 2022 by JohnTeee

[Sniper]

Check for #5 valves sealing properly, intake specifically.  Only way air can go out the carb if you are pressurizing #5 is with a valve not sealing, imo.

[JohnTeee]

Thanks Sniper! When I replaced valves 10 years ago, I no longer recall how I figured out they were bad (bent shaft, warped valve). It occurred to me AFTER I pulled the head, that I could have check valve clearances vs. compression and maybe avoided some of this. How do I check for proper seating with the head off.

 

John

[Sniper]

Here's a video to watch

 

https://youtu.be/3GPyaFbPLpE?t=963

 

Where he laps the valves, you would use dykem, or a black sharpie to mark the seat then rotate the valve in that seat, like her did lapping them, and then observe the pattern.

 

You can also shine a very bright light up the port before you pull the valves and look for light between the valve and. seat, manifolds will have to be off to do either.

 

Edited November 16, 2022 by Sniper

[JohnTeee]

Thanks Sniper. I had to educate myself when I worked on the valves and head ten years ago and that knowledge just did not hang around when it wasn't getting used. <grin> Gives me an idea of how to check #5. I'm also watching a fella with a bunch of Flat Head 6 stuff, "Keith's Garage" and found a video Flathead Live Tappet Action & Valve Set Performance Gains, which has given me some idea of how to start out with a cold, non-running engine. I have the 'aft' valve cover off and getting ready to play.

 

Thanks again!

 

John

[Bob Riding]

Another satisfied @keithb7 viewer!

[JohnTeee]

Bob, even I can understand them! ?

 

John

[keithb7]

Thanks for the positive words folks. @JohnTeee I have uploaded multiple videos on valve sets I have done over the past few years. I hope you find them useful. One of my goals is to keep things simple. I begin by stripping down a topic so my little, under-utilized brain can grasp whats going on. Lol. Once I feel I have a pretty good understanding, I think, why not make a video for others to learn as I have learned?

[LeRoy]

18 hours ago, keithb7 said:

Thanks for the positive words folks. @JohnTeee I have uploaded multiple videos on valve sets I have done over the past few years. I hope you find them useful. One of my goals is to keep things simple. I begin by stripping down a topic so my little, under-utilized brain can grasp whats going on. Lol. Once I feel I have a pretty good understanding, I think, why not make a video for others to learn as I have learned?

 

18 hours ago, keithb7 said:

Thanks for the positive words folks. @JohnTeee I have uploaded multiple videos on valve sets I have done over the past few years. I hope you find them useful. One of my goals is to keep things simple. I begin by stripping down a topic so my little, under-utilized brain can grasp whats going on. Lol. Once I feel I have a pretty good understanding, I think, why not make a video for others to learn as I have learned?

I'm planning to crawl in the fender in a month or so and give it a go. I set them while on an engine stand, now that I've got several hundred miles on the rebuild I'm going to give them a check and see if I can reduce the tick a little. I've watched your vids and I think you gave me the courage to give it a shot. (Im told its a thin line between courage and stupidity:) )

Edited November 18, 2022 by LeRoy

[keithb7]

Naw. There’s nothing to it. Go for it. The most important thing is understanding TDC for each piston and 100% confirming both valves are fully closed. As mentioned in my videos, you will feel tappet clearances at this point, by wiggling the tappet up and down. 
 

Start at #1, precisely followed by 5,3,6,2,4. 
 

Trial and error is character building and gains confidence. Never again pay someone to do a valve set. Do it 3x and you’ll be better at a flathead set, than the average pro today. 

When you think you are done, leave the inner fender window out. Drive it for a few days. Just incase you need to go back in there again. I seem to recall I got distracted with other work and drove without the inner fender window for 6 months. 

Once you feel swelled with pride and are reaping the benefits of your new developed skills, reassemble the inner fender window and join me in the “pride lounge” for a beer. 

[JohnTeee]

I thought I'd post an update on what I've found . . .

 

As you will recall, my mechanic reported a leak down failure from 5 into 6 and the intake. Suspected head gasket or valves. Sniper recommended setting the valve lash.

 

Following the manual . . .

Quote

Exhaust valve clearance .010
Intake valve clearance .008

and added 0.002” to the valve lash intake and exhaust clearances to account for a cold engine.

 

Since the head was off, I was able to visually run each piston to TDC on the compression cycle, giving me lash on both the intake and exhaust valves. Set all six cylinders this way. Spun the engine around around several times and rechecked the valves . . . and got some funky results. Mostly on #5, having lost it's lash. Tried another round, using the recommended:

 

Stage A, #1 and #6 at TDC, #1 in firing position
Stage B, #1 and #6 at TDC, #6 in firing position
To move from Stage A to B, manually turn the engine 1 revolution.

Stage A – Adjust #1 Both valves, #2 Inlet valve, #3 Exhaust Valve, #4 Inlet valve, #5 Both valves.
Stage B – Adjust #2 Both valves, #3 Inlet valve, #4 Exhaust valve, #5 Inlet valve, #6 Both valves.

 

It all looked good. Spun the engine several times and had some off settings, I think mostly lost lash on #5 again.

 

I was curious about any possible improvement in compression test, to put the head back on, with the old gasket and some grease on one side. Did not want to put a new gasket on, just to check and then throw it away and have to buy another. Did not torque - no particular reason, guess I just wanted to do a quick test. Old values December 2017
#1 -100; #2 – 110; #3 – 107; #4 – 110; #5 - 100; #6 – 112

 

Since this has set for 5 years, I had added a dollop of Marvel Mystery Oil to the open cylinders when I first pulled the head and spun it around. This was a couple of days before retesting. Today, after setting valve lash cold, with the extra 0.002” on each:
#1 -118; #2 – 110; #3 – 105; #4 – 105; #5 - 80; #6 – 85

 

Added oil to #5 and #6 and rechecked compression.

#5 – 100; #6 80

 

Torqued the head and rechecked, just to see what would happen.
#1 -115; #2 – 110; #3 – 105; #4 – 80; #5 - 135; #6 – 140

 

OK. Even after setting the valves, recheck #5 ad #6 were low. So, does that argue for head gasket? But after I added oil, #5 and #6 shot way up. Expeted? Do I really need to do a compression test with a warmed up running engine?

 

I have a leak down tester coming my way, should have been here today, hoped to be able to recheck with that and post those results. Should be here tomorrow.

 

I wanted to run what I had up the flagpole and see what happens. <grin>

 

Thanks for reading and any help.

 

John

 

[kencombs]

Looks like the valves are seating OK based on the last results.  Curious as to what happened to #4 after torquing the head though.  I wonder if that is repeatable?

You may have had a valve/seat with a little rust from sitting that caused the original leak test results.

 

 

I'll bet the leak down test will show some ring leakage, but It is likely that the rings may free up or seat better after it runs a bit since it was idle for a while.

 

None of the pics show any signs of head gasket failure.   I haven't plotted the valve sequence closely but it is possible the cylinder to cylinder leak indication was just a valve not sealing well on one and appearing on the other due to both cylinders having an intake off the seat at same time.  One due to a leak and the other due to valve timing.

 

I always get confused when trying to do things like that on paper.  But easy to do with the head off.  Just look at 5 and 6.  When either is in position for a leakdown test does the other have the intake off its seat?

[Los_Control]

When 5 & 6 showed 80-85 while the rest were 100+ .... I would suspect a leaking head gasket & 5-6 sharing compression.

 

Re-torquing the head & see a improvement .... might confirm this.

 

Buuuut ..... 135-140???   Thats a lot of compression for these old 6's .... makes me scratch my head and would want to check again.

Then #4 lost compression ..... I would be checking at least 3 times wondering if the gauge was accurate and produced same results consistently.

 

Same time it certainly has enough compression to run decent .... maybe run the engine a bit and re-torque the head ... put a few miles on the engine, then check the compression . .......  Just thinking the readings will change again after a few heat cycles and some miles on it. Might wait til then to re-check.

[Bob Riding]

@Los_Controlmakes excellent points. If it is indeed a P15 motor, the service manual states that a compression ratio of 6.8 to 1 should yield 105 lbs per cylinder with no more than a 10lb variance. That is true up to the P24 in 1954. In '55 and '56, the P26 and P28s C/R increased to 7.4/ 7.6 to 1, respectively, and 120-150 lbs per cylinder.

[Los_Control]

Good info there @Bob Riding.... makes a lot of sense also.

The way I understand our old rings, they tend to stick to the pistons after sitting for some time. Lowering compression.    Modern rings do not seem to do this?

So when you run the engine through heat cycles they can release & seal lifting compression .... I was told that the engines really like to run under load & while driving them will really loosen the rings up & seat the valves. ..... Letting it sit & idle helps to a certain point .... driving them really does the trick if any trick will happen.

 

If that is true, then after running & driving, the 100+ cylinders may rise and match the 5-6 cylinders.

I still imagine compression will change & probably improve after driving.

It has enough compression to run, I would run it then check the compression at a later date again.

[JohnTeee]

Well, you guys have given me some positives when I was fully expecting, 'Rebuild Time!'

 

My 'Leak Down' tester will be here today. I'll check with that and recheck compression now that it's been sitting a few days. Then will remove the head, again ?, closely inspect seats, maybe pop out a couple of valves, put it back together and install the new head gasket. See what happens from there.

 

In the meantime, I need to figure out an adapter from new fuel tank to fuel line. The new tank comes with something like a 3/8" fine thread female fuel connection and my existing fuel line connector is a 1/2" coarser male thread. I have a little fuel filter with the same 3/8" thread on one end and a rubber fuel line connector on the other. I can screw that into the tank, cut the male fuel fitting off and bridge it with a short piece of flexible fuel line . . .

 

 

Edited November 21, 2022 by JohnTeee

[Los_Control]

Hold off on doing anything with the tank .... there was a recent thread on just this issue & correct thread sizes etc ....  There is a exact fit npt size, while some threads will start but still not correct.

See if I cant find the thread .... answer is simple, also easy to mess up the threads.

 

That was easy ....

 

Also guess I'm not understanding why not run it as is .... why pull the head to check the valves?

Edited November 21, 2022 by Los_Control

[Sam Buchanan]

24 minutes ago, JohnTeee said:

 

In the meantime, I need to figure out an adapter from new fuel tank to fuel line. The new tank comes with something like a 3/8" fine thread female fuel connection and my existing fuel line connector is a 1/2" coarser male thread. I have a little fuel filter with the same 3/8" thread on one end and a rubber fuel line connector on the other. I can screw that into the tank, cut the male fuel fitting off and bridge it with a short piece of flexible fuel line . . .

 

 

 

Your new tank most likely has 1/4" NPT threads, that is why your filter will thread into it. You can either use the filter to connect the fuel line to the tank as you suggested or get a 1/4" NPT fitting with a barb, cut the flare fitting off the fuel line and connect the two with a short length of fuel hose. My car uses 5/16" fuel line, verify the OD of the fuel line on your car prior to buying the fitting and hose.

Edited November 21, 2022 by Sam Buchanan

[JohnTeee]

18 minutes ago, Los_Control said:

Hold off on doing anything with the tank .... there was a recent thread on just this issue & correct thread sizes etc ....  There is a exact fit npt size, while some threads will start but still not correct.

See if I cant find the thread .... answer is simple, also easy to mess up the threads.

 

That was easy ....

 

Also guess I'm not understanding why not run it as is .... why pull the head to check the valves?

Los_Control,

 

Thank you very much for that forum link and the info! I have to run out in a bit, so will look for a 1/4"-18 NPT/Flare fitting. Funny, as I was typing the message above, NPT fittings kept trying to flit through my brain. Had even Googled "NPT" to find that it's "National Pipe Thread".

 

I guess my only concern about running it as is has a two-fold answer.

One, the original concern was possibly a leaking head gasket and I would be putting the same one back in.

Which leads to the second part - reusing a head gasket. It DOES only have 500 miles on it, but can you get an effective, 'permanent' seal by reusing a head gasket? I had done some reading and was lead to believe that this is a 'No No', due to the crushable nature of the gasket.

 

Thanks again for all the help!

 

John

[Los_Control]

I was going to just post @Sam Buchanan reply in that thread,  as far as re-using the head gasket ..... that could explain why #4 lost compression.

There were some head gaskets you could re-use .... My1969 Triumph 650 motorcycle had a copper gasket you could anneal by heating it up to soften the copper & use it again.

 

I do not think your head gasket is meant to use over again .... carry on.

[JohnTeee]

31 minutes ago, Sam Buchanan said:

 

Your new tank most likely has 1/4" NPT threads, that is why your filter will thread into it. You can either use the filter to connect the fuel line to the tank as you suggested or get a 1/4" NPT fitting with a barb, cut the flare fitting off the fuel line and connect the two with a short length of fuel hose. My car uses 5/16" fuel line, verify the OD of the fuel line on your car prior to buying the fitting and hose.

Thanks Sam,

 

You and Los_Control were posting similar answers together. <grin>

 

Below is a carb line fitting. With that taper, to a 5/16" flare fitting, that looks like what I need. Just measured my fuel line and it is also 5/16". Hmmmm, wonder if I have some 5/16" fuel line sitting in my stash?

 

John

 

 

 

 

[kencombs]

2 hours ago, JohnTeee said:

Thanks Sam,

 

You and Los_Control were posting similar answers together. <grin>

 

Below is a carb line fitting. With that taper, to a 5/16" flare fitting, that looks like what I need. Just measured my fuel line and it is also 5/16". Hmmmm, wonder if I have some 5/16" fuel line sitting in my stash?

 

John

 

 

 

 

If that is a 5/16 hose barb the other end looks like a 1/8NPT fitting.   It will measure about 5/16 OD, but the pipe size is 1/8.  The tank looks like 1/4" pipe female.

[Sniper]

Years ago, I reused a steel shim head gasket that only had a few miles on it when I was working thru some issues on my 413.  Anyone that has ever pulled a BBM head from over the fender knows that's not a job you want to do often, if at all.  Sure enough, it blew and I got to redo it all over again.  Since then I have been a fan of new head gaskets, every time.  I also learned my lesson in regards to not reusing TTY headbolts on a Neon, same root cause, cheap owner (me). 

[Young Ed]

Once upon a time Dad and I bought a 52 Plymouth that turned out to have stuck valves. We reused that head gasket 3-4 times until we had a runner! We sprayed it with silver engine enamel each time 

[9 foot box]

   Since you determined that the tank fitting is 1/8” npt, you could use an inverted flare fitting to pipe size. You will still have to muscle your fuel line around to get the threads aligned but not as much as putting on a filter.