First attemt at rebuild on engine....1951 flathead straight 6

[burns5150]

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Hey Guys,

Im working on the 217 1951 Plymouth flat 6.

All this is new to me, and I am thinking about taking on my first rebuild job. Bear with my lack of knowledge, but I have got to start somewhere, right....

A few questions about whats going on before I pull engine. The car has sat for a good many years. But suprising, after running a gas line in a gas can and dumping some gas in top of the carb, it cranked up rather quick. There was a knock as soon as it ran, so I shut it down, only to try a few times to see where the noice was coming from. Sounded like it was right on the top, very high. (dont worry,only run it 10-15 seconds,..one or two times).

It ran real well and was suppose to have been a running car. Oil looked good, water looked fresh,plugs looked good. I took off the head and aside from some carbon, it appeared cleaner than I thought. Funny thing is that the front piston was very clean, even silver looking on top with little carbon. The other 5 looked dark, with more carbon build up. I looked at the valves hoping one was stuck making that be the sorce of my noice, but all where moving.

I have never build an engine and I know very little about flatheads. But I want to learn this, and dont want to send it to someone else.I really would like to stay with the original motor.....

What can I look for that would make that noice? Is it a for sure rebuild, or is there something that can be done before a pull ? Please dont tell me to just take it to a shop, I do want to learn and start somewhere...Thanks guys!!!

[aero3113]

Welcome! It sounds like you had a head gasket leak at the #1 piston.The water was getting into the cylinder and steam cleaning it. The knock you hear is it a knock or a ticking sound? The fuel pumps on these engines do make a ticking sound. Also how is the oil level? when I first got my car before I rebuilt the engine it had a knock, I topped off the oil and it went away.

[JoelOkie]

I think when it's sat for a long time you should crank the engine over some times before starting to make sure and get oiled up good. Were you able to see if you had oil pressure ? Good luck on your re-build. Joel

[burns5150]

I may have jumped the gun, and took the head off already. I didnt even check oil pressure before I did this. The knock is more of a bump/hit than a tapping, and sounded very close to the front/under the head(right where that shinny piston is at. I have put some pictures of the head and block to show where I am at.

I did however (and this may have not been very smart), turn the engine over a few times to see if I could find the sound or visual sign of the noice. It spun over smooth as it could be, and didnt make a sound or knock. After this, I tried to move the pistons within the cyclinder,and there was some play,but very little, in the pistons movement. Is this normal to have a little movement or should they be super "snug". Everything looks good, I hate to pull this if I dont have to.

Could a bearing in that piston be giving just enough play to hit the head?....Thanks in advance for all the help!!

[aero3113]

Since the head is off, I would drop the oil pan,pull the pistons,hone the cylinders and then replace the bearings and piston rings(also replace any bad pistons). That is what I did with my engine and it has been running great since. I knew nothing about flatheads when I started this work but found they are so easy to work on. You will learn lots when you do it yourself

[aero3113]

This will also give you a chance to clean all of the sludge in the bottom of the oil pan. Also pull the valve covers and clean the galleys out also.

[burns5150]

Can all this be done with the engine still in the car?....I was wondering earlier if this could be done just as easy with the engine still in place.

[pflaming]

Over the last PERIOD of time I just completed what you are anticipating. My suggestion is to PULL THE ENGINE. I also removed the front fenders, etc, easy to do on a B3B truck but well worth the effort. I too had NO knowledge of what to do, never opened up an engine. It's a lot of work but when you are done you know what you have, after all, it is the heart of the vehical. Good luck, do not be afraid to use the SEARCH, then cut and paste. Good luck. I just got mine running and drove the alley last week!!!!

In hindsight after what I went through, I think I would get that engine out put in on a stand, drop the pan and check the rods and bearings. IF they look solid I would put the pan and head back on, restart it and the stand and see what happens. I did that and had good oil pressure, so I pulled it apart new pistons, rings, reset the valves and all is good.

[JBNeal]

I reckon you can rebuild the engine with it still in the car. I think the trick is to remove the front wheels and have the frame up on jack stands so the front axle will drop out of the way to give ya some clearance to work. I've done this with both my '48 & '49 trucks, even replaced the valve guides in the '49 without pulling the block. It is a chore to maneuver around the fenders & frame & whutnot, but it can be done.

My concern with those pictures you've shown is the dark area on the head gasket between #1 & #2 cylinders. The steam cleaning of the combustion chamber from a coolant leak I understand, but I don't readily see where that leak would be, which makes me wonder if there is a crack in the block. This isn't necessarily the death knell for this engine, as a good machine shop can sleeve any cylinders that are in need.

When an old classic has been parked for many years, the thought rolls around in my noggin as to why the beast was parked in the first place. I've been lucky in that the two trucks I've resurrected were parked because they were burning oil from stuck rings & worn valve guides. My 584 International tractor was a different story, as it lost coolant slowly but I never could find any puddling. Sure enough, the head on that li'l diesel needed a lot of $$$ work done to it to put an end to that.

For this reason I prefer to tear down a motor to do a thorough inspection if it has sat dormant for an extended period for unknown reasons. This gives the mechanic the opportunity to find any internal wear &/or damage that could be catastrophic if not remedied pronto. It has given me the peace of mind that when I've put my projects on the road, I know for sure what cannot be wrong with it. Plus I've learned quite a bit by studying old shop manuals, parts manuals & the like to see what parts were used for years unchanged & what parts were redesigned every few years either because of performance or assembly/replacement issues.

[Flatie46]

Hello there, welcome to the forum. Before you get too far along pick up a box of zip lock bags and bag and tag this thing. It'll keep you organized and things are less likely to get lost. Where are you located?

[pflaming]

Flatie is 200% correct. Get a big pad of "post its". For each bag write on a post-it what is in that bag and put the post-it IN the bag. Include everything, cutoff/twisted off/ broken off bolts, washers, anti-squeak pads, etc.

I am re-attaching and did a very poor job. I finally took every loose part, bolt, strap, etc., put it on a table top and took what looked correct. I even sorted same bolts into color patterns, (dark ones for the engine / rusty for the body) that really helped, but still a bit confusing at times. But I have made it to the alley and back; so I will eventually win.

[burns5150]

Hello there, welcome to the forum. Before you get too far along pick up a box of zip lock bags and bag and tag this thing. It'll keep you organized and things are less likely to get lost. Where are you located?

Great infor guys!...I am located outside of Savannah Ga...There is not alot of people that I can go to for advice or anyone who has knowledge of old flatheads, i around this area. So, all the advice ya'll give is a great help and is priceless.

I am a pretty good body man, put never tackled an engine before. There is only one way to get this "lack of knowledge" out the way, is to get in there and get dirty. Keep the info coming, all the better. Great info guys!

[aero3113]

Can all this be done with the engine still in the car?....I was wondering earlier if this could be done just as easy with the engine still in place.

Yes,that is how I did mine:D

[greg g]

I admire your spirit and the your decision to get some old oil and grease under your fingernails. these engines are pretty simple and traight forward, but i would encourage you to get on E bay and get a service manual. Either original or repop. Also if you can find the parts book, the exploded views of the various assemblies can be very helpful.

The books are fairly inexpensive and will save you a lot of anxiety down the road.

http://motors.shop.ebay.com/Manuals-Literature-/6029/i.html?_nkw=194*+plymouth&_catref=1&_dmpt=Motors_Car_Truck_Parts_Accessories&_fln=1&_trksid=p4506.c0.m282

Also keep taking lots of pictures. Of stuff before during and after you dig into it.

Good luck

[boxer_inv]

Also keep taking lots of pictures. Of stuff before during and after you dig into it.

Absolutely invaluable. I can't begin to say how many times I referred to my pictures of 'before' and 'during' wiring looms and connections during my rewiring project. Digital photos cost you only the time it takes to shoot them - but they are worth more than the 1000 words claimed!!

Also, the zip-lock bag thing is essential for me.

Good luck on your project - tackle it head on!!

[Jim Saraceno]

Go to the following link and download the four files. They contain an article about rebuilding a flathead six.

http://www.esnips.com/web/PlymouthFlatheadSixsBusinessFiles

[greg g]

When you get to the pistons and connecting rods, be very attentive. the cylinders are bored in pairs and the pair partners must be kept in tact and in order as the connecting rods are offset to allow this set up. As you can see from the pictures you posted the space between the pairs is not equal along the lenght of the block with the amout of metal between 1 and 2 being much thinner than the space between 2 and 3. The crankshaft eds of the con rods are cast to accommodate this and must be reassembled i their pairs and with the proper allignment with the pair. This is basically the only "tricky" part of dissasembly and re assembly.

You might also want to look at member do Coatey photo bucket pages as he has extensive pictures of rebuild process. the album is linked from his postings and is broken down by section on his page. Also take a look at member blueskies website.

Between the two there are probably very few aspects of the process that are note detailed. Even though they built modified engines the processes will be germane to your project. As you can see my piston assemblies were clearly marked for reassembly.

Edited June 7, 2010 by greg g

[Merle Coggins]

Flatie is 200% correct. Get a big pad of "post its". For each bag write on a post-it what is in that bag and put the post-it IN the bag. Include everything, cutoff/twisted off/ broken off bolts, washers, anti-squeak pads, etc.

All you need is Ziploc storage bags with white the write on surface and a Sharpie. Write right on the bag what's in there. No paper notes to get dirty and hard to read.

[Don Coatney]

There is a guy in Elko, Ga who knows a little about these engines and may be able to help. He will most likely chime in here.

http://maps.google.com/maps?f=d&source=s_d&saddr=Pine+St&daddr=&geocode=FdBa7QEdmasC-w&hl=en&mra=ls&sll=32.331093,-83.706379&sspn=0.017116,0.038409&ie=UTF8&ll=32.33241,-83.710818&spn=0,0.002401&t=h&z=19&layer=tc&cbll=32.332379,-83.710722&panoid=0WH6c7cYJRI4Yx64PNlHGQ&cbp=12,44.68,,0,3.8

Also contact forum member Lou Earle who lives in Dublin, Ga

[Plymouthy Adams]

and Louman is just a tad past halfway between his place and mine...I have sent Burns5150 an intro and link to join and view the local Georgia group..we have a couple more folks on that side of the state who have not yet placed their name amoung the group..they are not as active here but owners nontheless

[190bearplace]

I know I will catch a lot of flack for this but I would mill the head and put it back together. You have jumped the gun a little, already pulling the head, but by the pictures the only obvious problem is the head gasket. Doing the gasket is quick, good practice, and may take care of all your problems. If not, you can have someone experienced listen to it and then make a plan of attack.

[pflaming]

I agree with 190bearplace, because that is what I did, saved me alot of work. Good luck, these old engines are really quite simple.

[burns5150]

Thanks a million guys! There is some great info coming in and I am all ears. I feel like I can take this on now. I am still open for more info and am glad to recieve it.

I would like to think it would be just a head gasket, that sure would be nice. Those piston, especially the front shiny one, has about 1/8" of play, but they all can be moved but barely. Maybe it should be rebuilt , like most said, to have peace of mind on the road. Plus, I do want to give one a try, so why not now!

Still open for info and ideas....

[Reg Evans]

I know I will catch a lot of flack for this but I would mill the head and put it back together. You have jumped the gun a little, already pulling the head, but by the pictures the only obvious problem is the head gasket. Doing the gasket is quick, good practice, and may take care of all your problems. If not, you can have someone experienced listen to it and then make a plan of attack.

I agree with this advice too. I'd button it back up and run it up to operating temp. Then pour small amounts of water in the carb while it is running at approx. 2000 rpm's to remove all that carbon buildup. Dropping and cleaning out the oil pan is a good idea too. Don't spend money yet. You might not need to.

[pflaming]

This was what I started with and ended with. Same block and radiator. I had to get a head. Go to you-tube Mopar Flattie 6 for videos of before new piston/rings and after new pistons/rings. Don't underestimate these old engines, they are tough.

Edit: What encouraged me was that the oil was black, no evidence of water: and that was with a block that had been setting for 17 years with no head and no exhaust or intake manifolds. I figured if the water hadn't got in in that amount of time, something must be quite sound. Water in oil looks a ghastly brown, its very obvious.

Edited October 1, 2017 by pflaming