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Message |
    
David Cracknell
Member
Username: stromzilla
Post Number: 18
Registered: 06-2009
| | Posted on Sunday, June 28, 2009 - 08:01 pm: | 
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I'm on a tight budget but I don't want to do anything stupid either. With my engine rebuild I'm hoping to reuse the pistons and install new rings. What are your thoughts regarding max piston skirt clearance for a piston reuse? The book gives a range of .0045" to .0075". My thought is if the clearance comes in at .006" or less, then I might be good to go with the current pistons. What do you guys think? |
Dcramer
Advanced Member
Username: dcramer
Post Number: 134
Registered: 05-2008
| | Posted on Sunday, June 28, 2009 - 09:00 pm: |
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My thoughts are that you need to get it apart and see what's wrong with it. Outboards seldom wear out. A more common failure is a carboned up piston that is scuffed and scratched once the rings are coked up and stuck. In that case, a piston replacement is warrented regardless of the skirt clearance. |
David Cracknell
Member
Username: stromzilla
Post Number: 19
Registered: 06-2009
| | Posted on Sunday, June 28, 2009 - 09:41 pm: |
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I agree with your comments. However, in looking at the pistons and crank, I see nothing that says these parts can't be reused. The pistons show normal wear with no scuffing. The compression was also good prior to teardown showing 120 psi or higher on all 4. At this point I'm inclined to believe the gel seal gave out and/or the crank seals crapped out which would not allow the lower end to build pressure thus not getting air/fuel to the topend...but I'm still looking for the culprit. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3844
Registered: 04-2006
| | Posted on Sunday, June 28, 2009 - 10:08 pm: |
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Burned gel-seal and leaking crank cases are nothing new, it happens from time to time. Most common reason is crank case combustion caused by a lean condition. It might be from fouled carbs, it might be from low temperature (defective thermostats)++++ . It may not have occurred at the time the leakage starts, but at an earlier stage and then developed.
Simply re-seal and assemble, but be sure to really get all old gel-seal removed and surfaces 100% clean!!!
If the pistons are in good shapes, no scores or glazing (shiny spots at pressure areas), reuse them , but install new rings. Rings may look ok, may be within 'specs' but most likely lost tension.
Put it all together with a new impeller/water pump a well as new thermostats. have the carbs properly cleaned out. |
Joe Reeves
Senior Member
Username: joereeves
Post Number: 7533
Registered: 02-2001
| | Posted on Sunday, June 28, 2009 - 10:12 pm: |
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GelSeal failure, which is highly unlikely, would have the fuel/oil mixture blowing out the sides of the crankcase halves.
A failure of a crankcase upper or lower seal might affect one cylinder slightly but not all as there are crankcase/crankshaft seals between each cylinder.
If you're not getting the fuel/oil mixture to the pistons, the most likely cause is either fouled carburetors, or on that engine, a flawed electric choke. |
David Cracknell
Member
Username: stromzilla
Post Number: 20
Registered: 06-2009
| | Posted on Monday, June 29, 2009 - 06:56 am: |
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The Gel Seal definitely failed...witnessed the fuel blowing out the crankcase side myself while engine was cranking. Based off various feedback and parts in-hand, I'm betting on Morten Ringvold's assessment...Gel Seal failed over time due to excessive lean condition, probably from dirty jets. |
Joe Reeves
Senior Member
Username: joereeves
Post Number: 7541
Registered: 02-2001
| | Posted on Monday, June 29, 2009 - 09:02 am: |
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First time I've heard of GelSeal failing like that. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3847
Registered: 04-2006
| | Posted on Monday, June 29, 2009 - 09:47 am: |
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It happened in general to customers that kept on running with engines hat should have been taken care of long time ago. The V4 cross engines were the most vulnerable. In general when the by-pass cover gaskets started to leak/blow it would soon be time for splitting the engine and re-seal. |
David Cracknell
Member
Username: stromzilla
Post Number: 21
Registered: 06-2009
| | Posted on Monday, June 29, 2009 - 11:27 pm: |
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Based on what I'm running into which includes an unbelievable amount of carbon in the exhaust area, punched out cylinder (1), and the failed Gel Seal, I'm guessing one or more of the previous owners didn't have a clue or didn't care. The carbon buildup is pathetic and very characteristic of running cheap oil...learned the hardway about that, years ago. The punched-out cylinder, probably from a scuffed piston is usually resulting from dirty jets leading to lean-burn because of poor maintenance...failed Gel Seal fits right in. |
Doug Selbee
Advanced Member
Username: daselbee
Post Number: 309
Registered: 08-2008
| | Posted on Tuesday, June 30, 2009 - 08:33 am: |
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Have you considered cylinder out of round issues?
When I measured my block, I found all six cylinders failing the spec for maximum out of round.
I had to bore all six to .020 over.
It was then that I realized that the motor was definitely "worn out". I don't know how many hours were on it. |
Joe Reeves
Senior Member
Username: joereeves
Post Number: 7551
Registered: 02-2001
| | Posted on Tuesday, June 30, 2009 - 11:30 am: |
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David..... The "unbelievable amount of carbon in the exhaust area" you mention.... if that is indeed carbon (regular hard carbon), that's one thing, BUT........
Should that "carbon" be a more soft waxy like build up (a lot of it). That would be the result of a engine condition we refer to as "lugging". This condition presents itself when (usually) a wrong propeller (too much pitch) is installed that prevents the engine from obtaining its full operating rpm range at full throttle.
Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:
http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store |
David Cracknell
Member
Username: stromzilla
Post Number: 23
Registered: 06-2009
| | Posted on Tuesday, June 30, 2009 - 02:00 pm: |
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Doug - That's interesting about your engine being out of round. We measured the cylinders yesterday and there was .001 to .002" wear so I should be good to go for now.
Joe - I never realized that a lugging engine can develop the soft-like carbon. I would classify the carbon in my engine being the harder variety...and it was thick. The prop on this engine which is hanging on the boat at the moment and I've been assuming has always been with this boat (Carlson CVX-16) is actually under-pitched (13"x19") because it over-revs @ wot. I'm fairly convinced that a combinatin of time and low quality oil has contributed to what I believe to be an excessive amount of carbon buildup. |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1479
Registered: 05-2001
| | Posted on Tuesday, June 30, 2009 - 06:52 pm: |
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Fuel blowing out the side of the crankcase while cranking? Sounds strange to me. More like a bad fit between crankcase halves. Gel seal will only hold if the surfaces are a very good match. It will not bridge any gap at all.
Leaking piston rings or timing that is advanced too far will make it worse.
It sounds like the pistons are good enough to use. |
Andrew Mackhrandilal
Advanced Member
Username: nymack66
Post Number: 140
Registered: 10-2007
| | Posted on Tuesday, June 30, 2009 - 09:30 pm: |
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Note you must check the crankcase now if its warp. Follow the manual very simple to do.. |
william g moore jr
Advanced Member
Username: william_m
Post Number: 234
Registered: 05-2009
| | Posted on Tuesday, June 30, 2009 - 09:39 pm: |
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We had "force" (theres that word again) that would do that. We switched from Gel-seal to grey seal and never had a problem again. The grey would squish out better and keep the main bearing clearances much tighter. Used this stuff after working on Subaru's and Vw air cooled cases. You still had to scurry as it would set up as fast as the gel-seal. But never with as much dimension as the grey seal. |
David Cracknell
Member
Username: stromzilla
Post Number: 24
Registered: 06-2009
| | Posted on Wednesday, July 01, 2009 - 05:42 pm: |
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I think I'm screwed. When I place the crankcase mating halves together (without crank) I can fit a .004" feeler guage in between at the corner. And I don't think that is a good situation. Any suggestions? I'm already looking into resurfacing/boring but I have a feeling that will be cost prohibitive for me. And I was really enjoying this project. Now it's a total bummer. |
Andrew Mackhrandilal
Advanced Member
Username: nymack66
Post Number: 141
Registered: 10-2007
| | Posted on Wednesday, July 01, 2009 - 11:06 pm: |
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No you are NOT , have a machine shop "plane it down" or build it up ! |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1481
Registered: 05-2001
| | Posted on Thursday, July 02, 2009 - 03:51 pm: |
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I think you could get away with using a hard sealer instead of gel seal ( I do this all the time on rebuilds ). Hard setting permatex will do the job. Forget about machining. |
David Cracknell
Member
Username: stromzilla
Post Number: 25
Registered: 06-2009
| | Posted on Thursday, July 02, 2009 - 06:08 pm: |
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Tony - Now that's an interesting thought. I would not have trust in using gel seal with .004" warp but using a hard seal...at least I'd feel better if I were to forego the machining. You also mentioned leaking pistons...1 piston had a stuck ring (bottom ring) and a second piston with a ring starting to get stuck. This engine had been running lean from dirty carbs, creating excess carbon from using cheap oil adding to the sticky ring scenario, and then the blowby adding to the situation. How the heck did this engine survive this long? Why is it people will spend thousands on equipment and turn around to buy cheap-crap oil for their prized toys only to save a couple dollars? Ignorance is bliss. |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1483
Registered: 05-2001
| | Posted on Friday, July 03, 2009 - 06:32 pm: |
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I don't even bother with Gel Seal on a rebuild. Soft permatex works fine. If I feel the clearance is too great I use the hard setting permatex. |
David Cracknell
Member
Username: stromzilla
Post Number: 26
Registered: 06-2009
| | Posted on Friday, July 03, 2009 - 07:33 pm: |
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Tony - What do you consider to be too great of a clearance? As I stated earlier, my clearance is .004". Would you use soft or hard Permatex with .004"? |
william g moore jr
Advanced Member
Username: william_m
Post Number: 248
Registered: 05-2009
| | Posted on Friday, July 03, 2009 - 11:17 pm: |
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Have to agree with tony. Gel-seal will cause more clearance problems than it cures. The Spaghetti seal round the case should hold just fine, but if your still worried, spray some paint on one side and do a dry run and see where the paint transfers. Then "draw file " The area for a closer fit. Remember .004 is just 1 stroke of the file. Again I recommend grey seal as it stays runnier longer and seals fine. leaving no excess in the parting line. Have used it for 20 years on VW, Subaru's and all makes of Outboards. |
jamie campbell
Advanced Member
Username: outboard_doctor
Post Number: 451
Registered: 02-2009
| | Posted on Saturday, July 04, 2009 - 01:29 am: |
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I would NOT use anything other than Loctit 515 it will eliminate a gasket up to 15 thou in thickness. It is the "RIGHT" stuff to use.
Loctite® Gasket Maker 515™ Flange Sealant is a flexible, gasketing material for use on rigid machined flanges with less than 0.015" gap. OEM approved ™ use where OEs specify 515 or ™anaerobic™ gasket (cures in absence of air). Eliminates preformed, pre-cut, paper, rubber and cork gaskets. |
David Cracknell
Member
Username: stromzilla
Post Number: 27
Registered: 06-2009
| | Posted on Saturday, July 04, 2009 - 08:14 am: |
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William - I don't believe my engine case uses the spaghetti seal. Can you fill me in a bit more on "Gray Seal"? What is the brand name, and where can you find it? I was in the auto parts store the other day and could not find it.
Jamie - I didn't even know about the 515. I've been studying the data sheet on the 518. By the way the max gap is .0098"...still well within my .004". In looking at both it appears the only difference is in the flex capability of the 515, which I think I'd prefer. Is that why you'd use it over the 518? |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3884
Registered: 04-2006
| | Posted on Saturday, July 04, 2009 - 08:38 am: |
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I think 515 and Gel Seal II is more or less the same. Loc Tite once used to have a similar product called Master Gasket where the 'base' was the same, but they had added micro-balloons in order to make it able to fill a bigger gap. The problem with all of them is that they deteriorate over time and with exposure to fuel and HEAT! In short, if You have a problem with crank-case combustion, it 'burns' out. The advantage with it, is that it handles better the pulsing over-under pressure that You have in a two-stroke crank case. This might be a problem with the other sealing types mentioned. In Your case I would have glued a piece of wet-sand paper (800 grid)on apiece of glass (bigger than the crank-case, and carefully planned both halves. Then use Gel-Seal or 515. |
David Cracknell
Member
Username: stromzilla
Post Number: 28
Registered: 06-2009
| | Posted on Saturday, July 04, 2009 - 08:47 am: |
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I've been receiving some interesting and enlightning information from many, and it's well appreciated, so I thought I'd update the thread with what my current plans are. It's obvious there are many who feel machining in my application is not the way to go with having a .004" gap. In light of my situation along with my engineering background regarding materials, I've decided to forego the machining and instead choose the best sealant and draw the cases together during torque-down. I get the feeling (but can't prove it) that there are more warped cases on older engines than some are willing to admit, all due to the constant heating/cooling cycle that all engines go through during the course of their life. In talking with a machine shop he thinks he can do it but it's not his specialty. If my case gets messed up then I am truly screwed and so I'm a bit gun-shy about machining. I know it can be done, but between the risk, cost, knowing I only have a .004" gap (some of which will draw out), and available sealant band-aids, I feel that using it as is for now is the better choice. Now I have to choose the sealant. The concern I have is obviously it's capability along with minimizing the unwanted shimming (from sealant) when the parts get mated and torqued. The products I'm leaning on are the Loctite 518, 515, Permatex soft, Permatex hard, and Gel Seal. The only data sheet I can't seem to get my hands on is for the Gel Seal. Please keep the feedback coming. I have learned a lot from all who've responded to my thread and in private. Thanks again. David. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3885
Registered: 04-2006
| | Posted on Saturday, July 04, 2009 - 09:04 am: |
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Go to the loc-tite side and download the data sheet of the 515 and 518.( google loc tite 515) Then You might understand my comment about heat and fuel. The biggest mistake done when applying gel-seal/loc-tite is that people make a 'string' and do not even it out thin enough like a film. At the factory they use a 'screen' to apply with which makes it easier. The most important is a clean surface! |
william g moore jr
Advanced Member
Username: william_m
Post Number: 255
Registered: 05-2009
| | Posted on Saturday, July 04, 2009 - 09:38 am: |
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Morten has it right when he says "clean surface" and my only trouble with get seal was with the people who would string in a bead and just bolt it together, but it would build up a .010 gap of gel-seal which would break down and have big main clearances.
Found the grey-- it's true name is "ultra-Grey. from permatex. item #82194
It does take a day to cure. It was a warrantee required sealant for Suburu back in the day.
If the spaghetti seal didn't jump right out at you -you probably don't have it. It was expensive to put in a design, and apparently not all that effective. The earlier Johnson Evinrudes used it in the crank case parting line seal and on their early lower unit halfs, Chrysler followed suit. |
Tony Delio
Senior Member
Username: tonyob
Post Number: 1484
Registered: 05-2001
| | Posted on Saturday, July 04, 2009 - 12:57 pm: |
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.004" is a wide gap for a crankcase. Of course it will decrease when you torque the fastenings, but this will tend to force whatever sealer you use out of the areas where there is no gap.
So, the best approach is use hard sealer, tighten the fastenings just until you feel contact, let the sealer cure for a day, and then torque down.
This is the point where someone usually comments that this will change the clearances of the crankshaft bearings. Go figure. |
william g moore jr
Advanced Member
Username: william_m
Post Number: 258
Registered: 05-2009
| | Posted on Saturday, July 04, 2009 - 03:23 pm: |
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Have to disagree with tony on that .004 is a wide gap. If you set that engine case 1/2 in the shade and 1/2 in the sun it would warp way more that .004.
So would compare all the sealers, and choose for your self.
Might move to another forum as we all seem to have a favorite here. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3891
Registered: 04-2006
| | Posted on Saturday, July 04, 2009 - 07:55 pm: |
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I have some difficulties accepting this talk of bearing clearance. It would take more pressure/gap than what is here to compress the outer bearing races in a way that clearance will be changed! This is not a 4-stroke with loose bearing shells and dependable of oil-film pressure. The only question is which sealant will seal off in a proper way! |
william g moore jr
Advanced Member
Username: william_m
Post Number: 259
Registered: 05-2009
| | Posted on Saturday, July 04, 2009 - 09:02 pm: |
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I can share your confusion as those caged rollers and fractured races are really loose and a good coat of oil keeps them going. If the bearings were the only thing to worry about, you would not have a problem with even .010 clearance in the bores.
However- excess clearance equals egg shaped bores. This then exercises the top and bottom seal at idle speeds and is detrimental to the way the internal crank seals are performing. A round laverenth seal, or even slip ring seals would not hold much fuel load in their chamber if they had .010 seepage to the a joining cylinders.
The outer races (held together for assembly by a blind snap ring) will also start to dance around.
So I feel that getting rid of as much sealant in a crankcase parting line is a real good idea. |
David Cracknell
Member
Username: stromzilla
Post Number: 29
Registered: 06-2009
| | Posted on Saturday, July 04, 2009 - 10:29 pm: |
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William - Just finished reading the data sheet on Grey Seal and I have a couple of concerns. It's been drilled into me that I should not use an RTV for the crankcase flange assy. And the data sheet specifically says not to use this product with anything that comes in contact with gasoline. You previously said you've been using this on outboard rebuilds...specifically at the crankcase assy? I like the performance info on this product right up to the point it says no contact with gasoline. There's a lot of gasoline flying around in the lower crank...you've not had any issues on your 2-stroke rebuilds in this area using Grey Seal? This product sounds like an excellent choice for all other areas...I'm just curious. Please let me hear about your specific experience with 2-stroke rebuilds using this product on the crankcase assy. The high-temp performance is outstanding!! |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3892
Registered: 04-2006
| | Posted on Saturday, July 04, 2009 - 10:58 pm: |
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The races are held in place by pins and will not start 'dancing around'. What further more keeps them in place is the torque of the center bolts, and I suspect that the 'problem' on this case might be the clearance on the outer flange. It is all designed for using Gel Seal and provided it is applied according to specs there will be no build up of clearance. The only question might be if the Gel Seal might hold on the outer flange. |
David Cracknell
Member
Username: stromzilla
Post Number: 30
Registered: 06-2009
| | Posted on Saturday, July 04, 2009 - 11:30 pm: |
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Morten - You bring up an interesting point. The gap I have been referencing is definitely on the outside flange. Tomorrow I will take a closer look towards the inside where the heavier bolts clamp down.
I've been studying the Loctite 515 and 518 gel seal. In an aircraft engine forum they said that 515 is NOT to be used on aluminum and only 518 of the 2 should be used. I'm scratching my head on that one...went back to the data sheet and nowhere (that I can see) does it say not to use with aluminum. However, when you look at the strength graphs showing the products on alum vs steel, the 515 shows a shear strength that's 50% on alum. to steel probably due to the increased flexibility built into the product, and 518 is about 75% on alum compared to steel. NOWHERE does it say on either product that you can't use on aluminum. I've submitted a question to Loctite's tech support. I'll let you know what they have to say. |
Morten Ringvold
Senior Member
Username: haffiman37
Post Number: 3893
Registered: 04-2006
| | Posted on Saturday, July 04, 2009 - 11:39 pm: |
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The answer will probably be: If used on aluminum You are recommended to use a primer.(Loc Tite Primer). |
David Cracknell
Member
Username: stromzilla
Post Number: 31
Registered: 06-2009
| | Posted on Monday, July 06, 2009 - 09:40 am: |
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Here's the response from Henkel regarding Loctite 515 & 518 for aluminum crankcase assy applications.
David,
These products are very similar in chemistry with only minor physical differences. 518 is thicker in viscosity which can be considered easier to apply but it also takes longer to cure than 515. You might find that Loctite 515 is more readily available and easier to find locally but either product should work for your appplication.
Best regards
It sounds to me as though either can be used. The 515 has less strength but is more elastic, along with being a bit thinner which could also be a good thing. |
