Crank Seal Plasticizer Experiment

Below are excerpts from


Sep 26, 2009

I know this is a 1 in a million shot. Has anyone ever done this and it worked, if so what did you use, and how did you get it in and out of crankcase.
I figured since it has to come apart anyway why not take a shot. My thinking was to run the piston up to TDC and pour in through intake, let it sit a few days or a week and see what happens. I have heard brake fluid swells rubber but was leaning toward something better. Maybe that Lucas power steering pump sealer, I have also seen some heavy equipment seal sealer.
I just don't have the extra 600 bucks for a new crank and thought something might get it through 'till winter and I can do it right. Any ideas greatly apreciated!


Sep 26, 2009

I found a couple of heavy equipment type hydraulic lift arm type sealers. One says it isn't petroliam based and it even has a money back gaurantee, kindy pricey at about 50 bucks a gallon.
Still thinking of a good way to apply/remove. I guess without the spark plug it might just "pump" it out by turning it over?
Way open to ideas.


Sep 27, 2009

This is the hydraulic seal saver I think I will try:

PorsheDave, that is sure a big gap. I wish I had the bucks for one of your cranks. I doubt this will work but if it buys me some riding time untill winter I would be happy. By the way, did you get my last email?
I also think I may but a bit of preasure, maybe 3psi, and turn the crank slowly so the sealer gets into the seal area, but judging by Dave's picture it shouldn't have any problem. Still thinking of ways to do it, I have several engines so if it goes bad I'm not in a pinch.


Sep 27, 2009

It was missing at idle on the two right cylinders, when you gave it gas it would pick them up, about 4k RPM. We made a preasure checker by sealing off the exhaust and carb mount, then with a schrader valve and a regulator preasurized each cylinder to about 6 psi, it wouldn't hold at all and you could hear air from the adjoining cylinder. The only thing that doesn't make sense is even the "good" cylinder leaked.
Carbs have new Sudco kits, new points/condensers, new plugs and new wires. The bike sat for 15 or so years when we found it, with some fiddling it fired right up on all three. Now that it has ran a bit it seems the seals are leaking.


Oct 02, 2009

I decided to go with the White Shepard stuff. I will post what comes of it, I don't expect much but you never know I guess.

Oct 11, 2009

Well, the sealer arrived and we plan to put it in this week and let it sit a couple of weeks. As a control I'm putting a new o-ring and an old o-ring, an old output seal thats hard and some rubber gas line that is ROCK hard in a container to soak as well. I will test them for size with the ones I didn't soak and durometer (racecar tire softness tester) to see what the differance is after and then again in a week or two to see if results last.

Bill (agentH2) said he can lend me his leakdown tester to check the engine. I still think it won't work but I figure to give it a good test. Any ideas on doing it any other ways? Thanks for the tip, the seals are rubber and we are checking vacume, I called it leakdown, duh.

PS. After only 24 hrs the o-ring is visually larger. It measured .030mm larger than the control, looks encouraging so far.


Oct 12, 2009

Only a real engine test and time will tell. If it buys me some time thats all I expect, certainly not a permanent fix. I just wanted a test I could see and inside the engine I won't know untill I fire it up.

If you read/believe the info with this stuff it states it is a platiciser (sp) and NOT a petroliam distolate (sp again) so it may be something differant. I KNOW it worked in my CAT loader lift seals, and they are 100's of PSI.
preasure and the dilution was 1 oz. to a gallon.

I'm going all or nothing and using it strait, thats why I wanted the o-ring test to make sure it didn't destroy the rubber using 100% sealer. Not that it applys but they do gaurantee it work but obviously not in this application.

I'm still pesomistic but a good start so far. I'm just doing this to maybe help some other guys that are in my same position and share what I find out, I've been helped here so much I figure it's the least I can do.


Oct 12, 2009

It's been about 2 years on the CAT lift seals. It also seemed to make the pump a bit less "growley" in the cold temps.

Oct 13, 2009

I just wanted tp post a pic of the o-ring that has been soaking for 2 days, I was going to measure it but no need really is easy to see how much bigger it is.
We put the stuff in the bike today, 6 oz. per cylinder, plan to leave at least a week while keeping an eye on the test pieces to make sure they don't start to get damaged. The fork seal in the test is way softer too, actually feels like a new one. I'll try post the pic: ... CN3187.jpg

Oct 13, 2009

I had an engine with the jugs off and the crank/rods still attached and I filled it up with a light oil, it took about 5.75 fiil it up past top of the crank, I thought it would take more too, not alot of extra room in there. Then we put 6 oz. in the engine.
I have a couple days lead time in the test parts so if they start to get too soft or degrade I will have time to get it out of the engine before damage.
I agree the next step is to see if the results last in the test parts. I plan to soak the test parts in gas/oil mix to see what happens too. Time will tell.
AgentH2 is going to try it on one too so we will shortly have another test.

Oct 14, 2009

It is the White Shepard in the gallon jug. I was amazed it worked in my loader so I thought I would try it in the bike.

What side effects did you have? Time will tell if it shrinks again. It says it's not a petroliam distalate (sp) so that may be differant than other things that swell seals, I know the Lucas is a PD and so are carb cleaners and the like.


Oct 18, 2009

I'm going to take the test parts out Tuesday and measure them and let them start to dry out.
I plan to take the stuff out of the engine Tuesday too. The plan is to suck out all we can with the vacume pump. Then do the preasure test. If that turns out OK put in some 2 stroke oil and mix that with the remaining sealer then put the bike on my roller starter with the plugs out and "pump" that out, add more two stroke and do that a couple of times so when it fires it has posative lubrication. Then put the plugs in and fire it up.
I may wait to do the preasure test untill after I get some 2 stroke oil in it or after we fire it, I don't think it matters either way.
I had a thought on putting the sealer in the gas and burning it. A good way to test may be to put a good bit (say more than you would in the bike) in an old briggs engine and see what builds up in the head/piston/valve. Maybe pop the head off and clean it up good before the test. I'd rather mess up a old briggs then a triple engine.


Oct 20, 2009

Well, it works. First of all the parts to test wicking showed it doesn't. The test parts are now drying out. After taking the sealer out and putting in about 3 oz. of 2 stroke and sucking all of that out we put it on the rollers and it fired up pretty quick, TONS of smoke and oil out the pipes. We did that about 4 times rotating plugs while we cleaned a set.

I rode it and it runs great, bottom end is back and starts on 1 kick. I know for sure it sealed after the first couple of minutes of riding it, like a whole new bike. I didn't have a chance to preasure check it yet and BUT it did seem to run worse near the end of the ride. Could be plugs are going, which is a real possibility as there was lots of oil in the cylinders to make sure I didn't ruin a bearing on the start up, OR it's loosing the seal after riding. I will do the preasure test tomarrow and put in a fresh set of plugs. Even if it doesn't fix mine I think it's worth a try going by the test pieces.

I will post what I find tomarrow.


Oct 21, 2009

Well, I found out what caused the lack of performance at the end of the test ride. It was out of gas! I put a gallon in and put it on "prime" by mistake. Filled it up and rode it again and all the performance is back and I'm a estatic. So far so great. Still not sure how long it will last but for now I would say 100% success.

Bill, bring it on over and we'll put it to it. The test pieces are the same as when I first took them out, the O-ring hasn't shrunk and the old fork seal is soft like a new one. If it works on your engine I'd say we are on to something.

I'm one happy mad scientist right now.


Oct 29, 2009

I'll keep posting, so far so good still. I have been starting it up everyday just to check it out. All the test parts are still nice and soft too.


Nov 15, 2009

Just an update. I took a short ride Saturday and all is well. It was cut short by a few nagging problems, countershaft seal still leaking and a brand new AGM battery failed. But the engine ran/idled/started fine. So far so good!

Dec 04, 2009

I start it up every week or so, along with my other bikes and either take a ride around the "block" (about 8 miles) or just let them get up to operating temp temp and let them run awhile.

I had another thought. The hydraulic seal is made to be put in the heavy equipment 1 oz. per gallon so it may help to put a couple of ounces in the oil tank with the 2 stroke. It's a lubricant so I think it would be OK on the bearings.

So far so good, if your thinking about it give it a try, worst case is it doesn't seal and your back to where you started.

Dec 19, 2009

They do make several products. The one I used was specifacally for sealing hydraulic seals like in heavy equipment, I think it's only available in gallons. I bet the other products are basically the same. Maybe a call to White Shepard would be a good idea just to be sure. I just got it from thier website, no one local wanted to order it.
BTW, started last week and all is still well.

Dec 24, 2009

I think a gallon will last a VERY long time. I'm glad some other guys are trying it out. At first I didn't know if I should post my plan and results but I thought pass or fail it would be interesting.

I still don't think it's a cure all but if your seals arn't real bad it may work or at least buy you some time.


Jan 25, 2010

Started up over the weekend. Not started since the last post, 1 kick. Still working good.

Jan 26, 2010

I put 1 oz. per quart in the injector oil. As little as it's ran I doubt it has even got the the pump.

Mar 07, 2010

Started today, 2 kicks, all good.


Mar 22, 2010

Started today, 1 kick.


Mar 23, 2010

It does smell a bit like brake fluid but I doubt brake fluid will work like this. I was a skeptic, thats why I did all the testing and such. Facts are facts and it's working in my bike. My air leak was so bad I could FEEL it in the other cylinders during the pump test, now nothing.

I also think a bit of swelling/softening may be good for the other old parts in the oil injection system. There is such a small concentration when mixed with the oil that I doubt it has much effect. To get the full effect it needs to be in the crank case full strength and let it soak for at least a few days. Why not try it, can't hurt anything. It may just work. I'm happy as crap with it.