crank hole plug problem

[R.White]

The threads in the (4 cylinder) crankcase nose are very worn down; presumably because of continued use of the crank (starting handle). The handle shouldn't foul these threads but they are beaten down so badly that the plug will not thread into the 1 5/8" hole. The plug has a copper crush wash and is a sacrificial part made from (aluminium) aluminum.

Finding a tap this size for hire will be difficult to say the least and such a tool will inevitably be machine driven. Even if a tap wrench large enough could be found ( I may have one) I imagine it would be difficult to keep square to the hole.

I have considered fitting a rubber lip seal but it may not work. As a temporary measure a cheap plastic fuel cap is retaining most of the oil but it doesn't seal and is unsatisfactory as some oil escapes all the time the engine is running.

Has anyone else had this difficulty and found a solution?

Ray.

Edited June 27, 2013 by R.White (see edit history)

[thirtyfourdodge]

The threads in the (4 cylinder) crankcase nose are very worn down; presumably because of continued use of the crank (starting handle). The handle shouldn't foul these threads but they are beaten down so badly that the plug will not thread into the 1 5/8" hole. The plug has a copper crush wash and is a sacrificial part made from (aluminium) aluminium.

Finding a tap this size for hire will be difficult to say the least and such a tool will inevitably be machine driven. Even if a tap wrench large enough could be found ( I may have one) I imagine it would be difficult to keep square to the hole. I suppose a machine shop could handle the engine block (large mill) but that would involve a lot of work and expense.

I have considered fitting a rubber lip seal but it may not work. As a temporary measure a cheap plastic fuel cap is retaining most of the oil but it doesn't seal and is unsatisfactory as some oil escapes all the time the engine is running.

Has anyone else had this difficulty and found a solution?

Ray.

Looks like you could remove the flange that is bolted to engine and take to machine shop. Looks like there may be a threaded sleeve in flange that could be replaced.

[R.White]

The thought had crossed my mind but the plate you can see is the front engine mounting.

Thanks for responding.

Ray.

Edited June 27, 2013 by R.White (see edit history)

[JayG]

Ray - I had mine apart and I should remember but .... I believe that if you place a jack under the front of the motor you can then remove the 3 bolts that hold the retaining flange on. Then the ball and sleeve will slide out from the front. Your right that this is the front motor mount but it is really a sleeve that fits into the front of the motor. Jay

[John McEwan]

That is correct. I had the same problem. A machine shop re-threaded the removable ball/sleeve with no problem.

[R.White]

Yes Jay, I have removed the three bolts with the engine supported as you describe and with the flange out of the way the ball shows through the cross member. I don't think the ball and sleeve will pull through the cross member though will it?

Ray

Edited June 27, 2013 by R.White (see edit history)

[JayG]

Ray - Use a jack under the front to relieve the pressure on the engine front support (ball/sleeve) and it should slide out. It's a tight fit and if it was installed with felt at any point in time it will be even tighter but it should slide forward.

[R.White]

Thanks Jay. I have the engine supported like you say but it really is a tight fit !!

I will have another go at it tomorrow.

Ray.

[MikeC5]

Hi Ray, here's what mine looked like with it removed.

[R.White]

Thanks Mike. So far I have not been able to loosen it. So long as it goes through the hole in the cross member or I will be flogging dead horse!

[Guest 1930]

Hi Ray, here's what mine looked like with it removed.

Nice picture Mike, couple questions, I am assuming that the very first horizontal gear is your oil pump drive, is that correct ? If so what supports it at the crankshaft end, ( upper end that we see in the picture ) Looks like it is machined to fit into something.

What is the deal with your water pump pulley, picture looks like it accepts a flat belt, have you retrofitted something, do you have any better pictures of the water pump to camshaft contact surface ?

It is my understanding at this point ( thanks to your great picture in part ) that your engine crank passes thru the front engine support ( the deal shown in Rays first post ) and engages the two little pins shown on the end of your crankshaft as is common to these early set-ups. Is that correct ?

I am not clear on how one would remove the bottom crank gear without disturbing the oil pump drive deal and without removing the crankshaft pin.

I am still un-clear on where the threads are supposed to be that the plug Ray shows is post number one are supposed to engage, can someone shed some light on this, a picture showing the different pieces in their correct order of assy would be nice.

Of course any more detailed pictures like this would be helpful.

[JayG]

Jason - That is the correct pulley on the water pump. Mine is the same. It actuallly took a wide flat belt. The threads are in the front end of the engine support.

[R.White]

Here is the sleeve/ball affair out of the engine. Jason, I think you can see more clearly now how the plug fits on the end of the ball part; when the crank is not in use it just stops some oil from leaking out. Clever how it combines with the front engine support.

Ray.

[Ron Lawson]

Ray The refurbished front mount are avaliable from Cd Dodge spares in Aust for $50 exchange You can find him on the web Ron

[R.White]

Nice picture Mike, couple questions, I am assuming that the very first horizontal gear is your oil pump drive, is that correct ? If so what supports it at the crankshaft end, ( upper end that we see in the picture ) Looks like it is machined to fit into something.

I am not clear on how one would remove the bottom crank gear without disturbing the oil pump drive deal and without removing the crankshaft pin.

Hi Jason. The spigot at the top of the oil pump drive fits in a bearing in a cover which here has been removed. I am sure it would be necessary to remove the oil pump and drive etc. should you wish to draw off the crankshaft gear.

Ron. Thanks for the info. It may come to that if I can't get the threads cleaned up here.

Ray.

Edited June 28, 2013 by R.White (see edit history)

[MikeC5]

Now that you have it out of there you have some options Ray. The edges could be weld built up and re-machined to proper threads or maybe oversize the hole for an insert that could be welded in or even installed with super loctite (the stuff that has to be heated in order to dis-assemble). Depending on shipping/duties costs that refurbished mount may be the most economical route. Here is another closer shot of the same area. The water pump gear has angled teeth that mesh with the cam gear (I believe this cam gear is a fiber one). There really is no adjustment for the gear backlash except for trying different gasket thickness on pump housing to block.

[R.White]

I took the sleeve/ball part and the plug to our local engine builders "Manx Engines" but was disappointed. They are not geared up to repair old stuff; more like fitters of disposable parts.

I looked up the gear sets for my small lathe but it only does Whitworth or Metric. I think the size is UNC. The threads might be UNF but I am not sure which.... Anyone know?

Tomorrow I will visit a friend who has said he should be able to help clean up the threads enough to enable the plug to be tightened. An exchange / replacement front mount may be the simplest solution in the end.

Ray.

Edited June 28, 2013 by R.White (see edit history)

[MikeC5]

Good luck Ray, I hope it can be salvaged.

[R.White]

Thanks Mike. I found one x 1 5/8" 16 tpi plug tap for sale. A bit pricey!

1 5 8 x 16 NS HSG H11 6fl Plug Tap x 5 1 4 OAL F 2 6 3 A FR10 | eBay

A few minutes lathe work, by comparison, should be better value. An exchange unit could be even more so.

Edited June 28, 2013 by R.White (see edit history)

[Guest 1930]

Jason - That is the correct pulley on the water pump. Mine is the same. It actuallly took a wide flat belt. The threads are in the front end of the engine support.

I had no idea, I guess I better start paying closer attention, thanks

[Guest 1930]

Here is the sleeve/ball affair out of the engine. Jason, I think you can see more clearly now how the plug fits on the end of the ball part; when the crank is not in use it just stops some oil from leaking out. Clever how it combines with the front engine support.

Ray.

Thanks Ray, so I take it that the threads are just missing altogether from the ball part, I sure do not see any.

[Guest 1930]

Thanks Mike. I found one x 1 5/8" 16 tpi plug tap for sale. A bit pricey!

1 5 8 x 16 NS HSG H11 6fl Plug Tap x 5 1 4 OAL F 2 6 3 A FR10 | eBay

A few minutes lathe work, by comparison, should be better value. An exchange unit could be even more so.

Id offer him 50 bucks, if its a no go than buy the re-furbushed one and be done with it, good luck

[R.White]

Id offer him 50 bucks, if its a no go than buy the re-furbushed one and be done with it, good luck

No harm in trying but he states only best offers considered on multiple purchases. $50 in his pocket better than an empty pocket!

[MikeC5]

What would it cost to ship over the pond though?

[R.White]

I have asked about that. You have to be careful when shipping costs are not included. The same thing applies to the exchange unit from Oz.

[R.White]

Thanks Ray, so I take it that the threads are just missing altogether from the ball part, I sure do not see any.

Perhaps this shot shows it better.

I am possibly clutching at straws. The guy I am taking it to will no doubt tell me if the threads can be saved. He is an experienced engineer with a lot of old car experience; mainly in racing.

If he says it requires building up and new threads made I will get the exchange unit from CD Dodge Spares in Oz. whatever the cost of postage. I have asked them for a price to the U.K. I should hear from them next week.

I have got the car set up so that it starts on the first pull of the crank; every time. I don't have a problem with hitting the threads. How anyone managed to batter these threads to death I hate to think.

Edited June 29, 2013 by R.White (see edit history)

[Pete K.]

Believe it or not, I've had good luck using a small Dremel type tool with a small cut-off wheel, !/2" dia. or so, and carefully go around the threads in the crank hole body to help restore damaged threads. Also, if you can find a plug the same size/thread as your crank hole COVER, cut a small notch into the threads perpendicular with a hack saw, so as to make a "self tapping" screw out of it. Then thread it into the body and you may have luck restoring the body threads. These are just ideas of a man with very shallow pockets.

[R.White]

Some good ideas there Pete. I am beginning to think in a more positive way with the various options that are open to me thanks to the input from you guys. Necessity is the mother of invention and now that having less disposable income is becoming a fact of life here in the U.K. too, we Brits will need to rediscover our traditional resourcefulness.

Although my mother's side of our family were pretty well heeled, my Dad was born into poverty and grew up in the '30's suffering privations we hope never to see again. Although he became successful in engineering Dad never let us forget how tough life used to be when he was young.

Ray.

[Pete K.]

Ray, I'm 5th generation American, Does that entitle me to "Native" American yet? Mom's side of family from England originally. Dad's side is 3rd generation German. This is why I'm always in turmoil with myself. Getting back to the crank hole situation, another home brew would be to acquire an expandable rubber & steel pipe plug, the kind plumbers use to close off an un-used pipe, maybe buried in a foundation wall. It has two steel washers with a shaft in the center and hex nut with the tapered rubber "cork" in between. When wrenched up, it expands and plugs well. It would look like the Dickens on the car but that hole needs to be sealed up well when driving. Without a seal there, it's a direct entrance to the bottom end of motor and will spew oil like no tomorrow when running. This I'm sure you know.

[R.White]

Hey Pete. Please don't take offence but I started to write a diatribe about the Germans then realised this was neither the time or the place! Yes I would say you are American through and through. Besides, there's no going back! Where you have a confusing mix of cultures in your ancestry, I have a volatile mix of Classes. My penniless working class father and my affluent middle class mother. As I read the situation, the landed families of America will place wealth ahead of breeding where the opposite is true here in England; especially with an 'old money' family. Times have changed though. The land and money have all but gone but the snobbery still remains! It drives me nuts! I believe I am truly classless and non the worse for it.

Whilst I thank you for your expanding plug idea, I already have a temporary stopper. My aim is to bring back the original engineering where I can. It's all good fun.

Ray.

[Pete K.]

Hi Ray, I have very thick skin--and I've heard it all. My uncle "Mac", (Wilbur K.) from Matamoras, Pennsylvania, flew 34 bombing missions over Germany. He lived to tell about it. He was with the 339th Squadron,96th bombing group, 8th Air Force (Army Air Corps). he flew as Captain, a Boeing # B17F-45-00. Serial# 42-3322. I don't know what airfield he was stationed at in England. He had his share of the dreaded German 77MM "flak". I had a piece of it that he brought back after the war.

Do you think it is possible to fabricate a slightly smaller threaded collar to go in place of the original crank hole and then find the same smaller, good looking steel crank cover that will screw into that? I'm running out of ideas!

[JayG]

Ray - Inserting a Helicoil is an option. The only thing is the largest sice is 1 1/2. That would mean machining down the crank hole cover and re threading that to match. helicoil,helicoil insert,helicoil inserts,heli-coil,helicoil kit,helicoil tool kit ,helicoil tap,helicoil india Here's a chart of the sizs available. Jay

[R.White]

There are some ingenious ideas there Guys. Today I visited an old friend in Nottingham. He has been in engineering all his life so knows a thing or two about threads. Usually he is supplying parts for Austin Sevens but was interested in my Dodge Brothers problem. When I showed him the sleeve/ball threads he thought there would be no problem. It depends on what I wanted to achieve. Yes, the threads could be recut but the question is how long they would last. They may strip out at the first attempt to tighten the plug. A better solution, he thought, was to let in a threaded collar. Once welded or brazed in place it would last for years.

When I explained that I could not cut a UNF thread on my old (1921) lathe because it only had gearing for Whitworth and metric, my friend showed me how close a 16 tpi Whitworth was to the American thread on the new plug. Another option would be to tig weld over the existing threads and re thread to the size required. Both ideas have been suggested here, I remember.

I could have left the part with him to get restored but because he is not in good health I felt it would be an imposition; besides which, he was confident in my abilities to do the job myself.

Back home I looked up the whitworth thread gear train for 16 tpi. I have one or two little problems with setting up the gears on my lathe but nothing that can't be sorted. As to pitch, I suppose as long as it matches the plug it should be O.K.

I am rather short of free time at the moment with the business taking priority over cars but hopefully I can escape to the garage for a while.

Ray.

[MikeC5]

Heli-Coils have saved my behind many times but even if they were available in this thread size the cost would be prohibitive if you had to buy the tools to do it and I think HCs need some minimum depth to diameter ratio to work properly. There are only 2 or 3 threads on this if I remember correctly. I think welding and re-machining is going to be the most economical especially if you have a lathe to do it with. I hope it works out Ray.

[RAH]

Ron, I'm glad you finally got that motor mount plug out of the chassis. There should be a flange that looks like a washer on the original hand crank that rides on the interior of that plug so there should be no contact with those threads. Sorry I do not have a pix readily available but have seen them on ebay occasionally. Good Luck.

Rodger "Dodger"

[TonyAus]

Hi Ray. Having a lathe, your problems are nearly over. I should point out that the only difference between US (UNF, UNC and English (Whitworth and BSF) is the form. US threads use a 60 degree form ( same as metric) and English use 55 degrees. Grind up a 60 degree cutter and you are away. I don't know about building up with weld. If you get hard spots the subsequent thread cutting could be impossible without using a carbide cutter. For what it is worth, my approach would be to turn out the existing thread, having previously made an insert ring with an internal flange to fit. Insert the ring from the rear and braze/silver solder in place. Re-cut the thread and shape the nose to the spherical form of the engine mount. If you do not feel confident in your ability you might consider contacting your local model engineering club for someone who could do the work. At the same time you could have a new plug made (or contact Myers for a replacement). Another thought, If the problem is only mangled threads you could turn up a short tap from a piece of gauge plate or other high carbon steel, cut a couple of raked edges around the periphery, then harden and temper it.

[R.White]

Rodger, yes the sleeve was really tight and I eventually removed it by getting behind the end of it from the inside. I have the original crank handle with the flange to which you refer so as I said previously, how the threads became so beaten up I can't imagine. I don't have a problem with hitting the threads.

TonyAus, This is what my engineering friend was explaining to me yesterday. I might do a bit of practise before taking the plunge with the actual part. I suppose another option would be to tin both surfaces and sweat them together. Another would be to heat shrink the parts together. I will have to get on with it.

Thankyou all.

Ray.

[MikeC5]

Silver solder is great stuff but it isn't cheap.. You also have to get the parts red hot for it to flow so a propane or mapp gas torch may not cut it. It isn't hard to do once you get it hot enough and use a silver brazing-specific flux. But I do think Tony's suggestion has the best chance of working well. It will also let you work with a piece of cylindrical bar stock making it easier to hold whilst cutting threads and triming the section for insert to the desired length.

[MikeC5]

On second thought since the joint doesn't require great strength, plumbing solder will probably suffice...

[R.White]

That's right Mike. I plan to turn up a suitable threaded collar; turn down the ball opening in the sleeve and sweat the two together with lead solder.

I have just discovered that the previous owner of my lathe had replaced the original 10 t.p.i. lead screw with an 8 t.p.i. one. Consequently, the information regarding the change wheels that I had been looking at was wrong for the machine as it is currently configured. I expect I was told about this when I bought the lathe but that was many years ago.

Now I have the set up right I can proceed. The sleeve is rather long for the chuck jaws to hold and the tool will probably chatter. I do however, have a brass tipped 'steady' which I can try.

Let's just see how it goes.

Ray.