1939 Plymouth Coupe Engine Hesitation

[1952B3b23]

A simple compression test will tell you lots. If the breathers are smoking chances are valve guides are worn. Are you smoking through the exhaust too? Probably ring issues if that's happening too.

How would i check if the valve guides are worn?

Yea it does smoke out the exhaust as well. I think the compression test is a great idea. I'll have to do that before pulling the engine.

Thanks,

-Chris

 

[smallfoot]

Chris, look around and see if you can find a good rendition of the compression test procedure along with a leak down test on a search. Generally speaking, smoke out the pipes indicates oil is getting by the rings and exiting as smoke during the cycle. If the breathers are smoking, generally oil is going by the valve stems and getting up in the valve covers and exiting thru the breathers. Use of a compression guage will indicate which cylinder or cylinders are lacking compression and adding a squirt of oil to the low pressure cylinders will momentarily increase the pressure there(indicating ring wear). Oil getting by the valves and up into the valve covers could be worn guides and or seals. The compression test will give you an idea if you have a single problem you can look for or overall wear through out the motor. I probably hashed the explanation all up but maybe you get the drift. Optimum pressure on cylinders with long mileage will seldom be reached. Really low pressure on all will indicate some serious rebuilding is needed. What I'd be looking for is fairly even pressures on all even if a little lower than normal. If you find one or two that are significantly lower than the others, you will know which ones to look more closely at and some teardown will be necessary...

 

[Old Iron]

You have to take the head off to check the guides so you might as well just take the engine apart and do a rebuild.

 

[Bamamav]

Hey guys, it's a flathead so the valves are in the block. The breather is on the crankcase, not a valve cover. Good suggestions, just don't fit his engine.
I would go with it simply being worn out and needing a rebuild. Compression is getting out of the cylinder, blowing by the rings and valves. Only thing that will fix it will be a complete overhaul, machining the bores and valve guides.

 

[1952B3b23]

Thanks fellas for the responses. Yea i think the bottom line is she is tired and needs to be rebuilt. I plan on pulling the engine and tranny this winter. That will allow me to not only rebuild the engine but paint both things. At the same time i can also clean up and paint my firewall. The plus side to all this is that at least once the rebuild is done ill have a strong running engine for the coming driving season.

Thanks again for the advice,

-Chris

 

[smallfoot]

Hoho! I'll go back to sleep...sorry wasn't paying attention

 

[Old Iron]

Yep, the valves are in the block, that's why I told him he had to remove the head.
The engine looks like 6 Briggs engines in a row

 

[bruno]

After a web search I found that ply and dodge made the flathead six until 59. The slant six came out in 60. The flat heads also were in the power wagons through the 60s. All of the flatheads are supposed to be a bolt for bolt bolt in swap. On some you have to use your flywheel. May be cheaper to find a good runner for cheap. The master rebuild kits are over $600. Add in machine work and you will probably be over a $1000. I don't know any of this for a fact as I got it off the web. Hope this helps.

 

[1952B3b23]

Smallfoot:

Its all good, i appreciate the comment either way.

Old Iron:

I literally just laughed out loud at your comment haha. It probably has as much power as 6 briggs engines in a row too.

bruno:

Ya know i've thought about this too and im glad you brought it up. The reason i have a soft spot for the 201 ci flat head is that its the original engine to the car. It baffles me how its survived 75 yrs already without being yanked out and replaced with something else. So i'd really like to keep it for now if it's not a a huge drain on the wallet. At some point i think it'd be cool to throw dual carbs and dual exhaust on the old girl for a little bit more pep and a tranny with OD. In stock form it only makes about 82 HP so she'll never be fast. Thankfully i dont care about going fast in this car, at some point i'd like to style it like a 1940s custom, low and slow. I'd rather look cool driving around town going 45 mph than blasting down the freeway (but thats just me).
In your web search did you find any master rebuild kits for the 201 ci flathead 6? If so i'd be interested in taking a look.

Another question i have is, how difficult is it to rebuild one of these? I've never done a total rebuild on an engine (except for a small lawn mower engine) but im eager and willing to learn. I cant imagine that its all that hard once the machine work is done by a shop.

Thanks everyone,

-Chris

 

[Old Iron]

I'll tell ya how easy it is.
My Grandfather was a mechanic and alcoholic so, the way he made his living was everyone who new him, new he done good work really reasonable.
When I was 7 years old, my Uncle was 11. He and I would get picked up by his dad, my Grandpa. He'd take us out to some farm house where sitting under a tree (hence shade tree mechanic) would be a Dodge, Plymouth or pretty much anything with a flathead in it.

He would sit in a lawn chair while we jumped up on the engine and started taking it apart. As the pistons would come out Grandpa would clean the ring grooves, install the rings, deglaze the cylinders and my Uncle and I would commence to putting it back together.
Then he would torque all the bolts.

Hey, no one told us we were too young or couldn't do it
Must have been a real show to the car owners

Our pay was a bologna (all the slices we wanted) sandwich and a whole quart of chocolate milk each [dr mmmmm still love those
If two snot nosed kids can do it, so can you [P

 

[bruno]

Only place I found rebuild kits for the 201ci was Kanter. Depending on your bore 3 1/8 or3 1/4 the master or deluxe kits vary in price from around $1,100 to $1,500 dollars. Deluxe kits have valves, springs and a few other things not included in the master kit. Throw in the machine work and it's a heart attack waiting to happen

 

[1952B3b23]

Old Iron:

Thanks for the words of encouragement and the cool story to go with it. I will be tackling this myself, I'm eager to do some learning.

Bruno:

Wow those are pricey rebuild kits. I've thought about this more and the plan is going to be do a compression test and see what that tells me. Then I'll go from there. If I can avoid having to pull the engine and doing a total rebuild I'm going to. I don't wanna break the bank on engine work cause I'd like to get it painted as well over the winter. So if I can get her back in shape without doing a total rebuild I'll be happy. Keeping my fingers crossed.

Thanks guys,

-Chris

 

[Killy_Killerton]

If I remember right adding a little marvells or atf to the gas keeps the organic seals "juicy"

 

[Bamamav]

Saw a flathead Mopar in the Hamb classifieds for sale, $600 I think. Might want to check it out. You could swap them out in a day or so, then build the original when you get the money.

 

[1952B3b23]

If I remember right adding a little marvells or atf to the gas keeps the organic seals "juicy"

Hmmmm never heard of that one.

-Chris

 

[1952B3b23]

Saw a flathead Mopar in the Hamb classifieds for sale, $600 I think. Might want to check it out. You could swap them out in a day or so, then build the original when you get the money.

I have a 218 ci from a '51 or '52 Plymouth that was in my '52 Dodge B3b that i pulled out. That thing is basically sitting in my garage just getting in my way. That would give me the benefit of a little more HP.

It ran decently when it was in the truck but i know that it could use new piston rings as it had blow by as well. Not as bad as the engine currently in the '39 though. I'm going to have to do some thinking about this. My wallet would probably like me a lot better if i went this route and just freshened up the 218.

What'd you guys think?

-Chris