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Author Topic: Help Os 40 v max bad water leak  (Read 2319 times)

dazzle

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Help Os 40 v max bad water leak
« on: May 24, 2007, 10:12:52 PM »

Went to start my os 40 today I have not tried engine before.
was on a test stand plus 5 gallon water container for cooling.
 glow plug loose as is a pig to turn over, engine filled up with water and peeing out by glowplug.
undone head bolts, Water cooled head is 2 pieces of aluminion fitted flush together
with no gasket  or sealer, (crap design)  Can I use something like hermatite as used on cars or simular.
on the 2 pieces. Any help Please & has anyone else encountered this problem.
Thanks dazzle (bob)
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bogstandard

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Re: Help Os 40 v max bad water leak
« Reply #1 on: May 24, 2007, 10:37:34 PM »

Hi Dazzle,
The first thing is to do a very minute check of all the castings, especially around screw holes and look for very small cracks or inclusions in the castings(these are little bits trapped inside the castings when being poured and when they are machined allow pathways to open).
If all is clear, I recommend HYLOMAR for the joints, you can get it from halfords for about 4 a tube, and follow the instructions precisely.

John
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #2 on: May 24, 2007, 11:50:04 PM »

Hi  john I got me magnifyer glass out & all looks ok, just got a pic of the 2 piece head,
marked 1 its these bits I need to seal, the gasket is missing from underneath w/c head
but is not the problem though I will need to seal that as well.
 as engine is early, os does not do spares, I will give that hylomar a go.
Many Thanks for your help
dazzle (bob)
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retro boats

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Re: Help Os 40 v max bad water leak
« Reply #3 on: May 25, 2007, 11:23:41 AM »

hi bob
 i have 6 if theese engines & have had no probs with  them normally the 2 part had grows together rather than leeks,
 be carefull if using a sealer or it may block the cooling ring onside
 get in touch with N CUP RACING for your head shims (gaskets) they are very i impotent to get the  compression correct
                                        regards steve
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #4 on: May 25, 2007, 10:46:19 PM »

Got the hylomar in a small motor factors that also does repairs/replacements etc
 main man says  it's the dogs nuts, compared with high temp silicon seal (too thick)
hermatite (goes watery). hylomar you only need a very thin film on both surfaces,
point noted on that steve thanks, I will also use it in place of gasket, It can be used
with or without a gasket, ie metal to metal plus is non hardening for easy removal of parts.
 I reckon that gasket was removed to give higher compression ratio, & more power,
= More speed till engine goes Bang. Also why it's a b*tch to turn over.
Busy with the brasso polishing now, safer than abrasive papers, I will  remember to
clean off with meths, isopropy, washup liquid and waterl.
Thanks again John & steve for your help  & info.
dazzle 
 
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HS93 (RIP)

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Re: Help Os 40 v max bad water leak
« Reply #5 on: May 25, 2007, 10:51:08 PM »

You may keep poping plugs if its not got the shim.

Peter
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #6 on: May 25, 2007, 11:04:16 PM »

Long as  its not too many peter I dont mind,
If the conrod or crankpin goes I will be in the cow pat
dazzle
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omra85

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Re: Help Os 40 v max bad water leak
« Reply #7 on: May 25, 2007, 11:24:48 PM »

Hi Bob
Glad you're sorted with the Hylomar, it's good stuff although usually you don't need anything on the joint as the two surfaces normally mate sufficiently to seal it.  Maybe someone was a bit 'fierce' getting it off in the past.
The joint you are referring to (between the water cooling head cover and the flange of the head button) is not altered to adjust compression.  The one that alters your head clearance is between the head button and the top rim of the cylinder liner (the ring under the letter G in 'cooling' on your parts diagram). This is either aluminium or, more usually, brass or copper. They are available in various thicknesses to allow you to 'pack' them under the head button to increase clearance.  If you haven't got at least one then I would suspect you have very high compression.
To check your head clearance you can either accurately measure the distance between the top of the liner and the top of the piston(at TDC) then take away the depth of the part of the head button which goes into the liner
OR (the method I prefer) -
Assemble the engine including the head.  Get a piece of soft solder (the normal electrical variety, about 1 - 1.5mm thick) and bend it into an 'L' shape with the lower part of the 'L' about 12mm long. Secure the engine in a vice or similar and feed the solder into the combustion area so that the end of the solder touches the side of the liner at the top. Carefully turn the engine over TDC using a spanner but taking EXTREME care to stop if the piston won't go over TDC without a lot of force.  Once the piston has gone over TDC remove the solder and measure the end of the flattened bit with a vernier.
For sports or racing engines using low nitro fuel the clearance should be between 15 and 20 thou.  This figure should increase the more nitro you use.  Hydros using 40% nitro can have up to 30thou clearance. For 5% nitro I usually aim for 18 thou clearance which is obtained by placing the appropriate thickness of shim(s) between the head and liner.
The more clearance you have, the more rpm you will get - BUT at the expense of poor throttling.
You may also find with a new engine that the piston 'binds' at the top of the stroke, making it hard to turn over.  This is normal and will reduce as the engine 'beds in' but it is advisable to use low throttle when initially running in the engine. Having said that, modern ABC piston and liners don't need much 'running in'. Usually about half to one hour at half throttle is enough.
Hope this helps
Danny

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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #8 on: May 26, 2007, 12:52:56 AM »

Hi Danny I know the 2 part w/c  head does not affect compression,  I was refering also to the ring by the letter g in cooling is missing
(o s says is part of gasket set), between head button & top rim of liner which as you said does affect head clearance,
engine is ciirca 1980  abc model, so is run in,
I will be using 10% nitro fuel & try different ratings of plug till I find what it likes best.
regards dazzle
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retro boats

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Re: Help Os 40 v max bad water leak
« Reply #9 on: May 26, 2007, 11:12:41 AM »

hi
 all my OS 40 VRM motors run rossi r5 plugs geared & direct drive
 the only weak point seems the conrod
                      steve
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #10 on: May 26, 2007, 11:54:56 AM »

Cheers steve, cowpats here I come.
will def be a cool cold or extra cold plug,
Wonder how standard os rods are if it was to break maybe a rod from
a 46vx-m might fit
dazzle
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retro boats

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Re: Help Os 40 v max bad water leak
« Reply #11 on: May 26, 2007, 02:12:45 PM »

hi bob
 are you fitting the os in the storm hull ?
       steve
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #12 on: May 26, 2007, 03:49:40 PM »

Hi steve I got the boat & engine at  an auction a few years ago,
it was in a bad state, & stripped it down & been rebuiding it, I dont know the make of hull,
just standard  b class multi hull approx 35/36 inch length x 12 inch wide,  geared submerged drive.
stainless steel chromed pipe. I used lightweight foam bouyancy front sides & rear, had to build a top cover.
All in weight without fuel, is now 3 kilos so is as light as an a class. I dont race no more,
Just want to see how fast I can get it to go.
regards dazzle
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glennb2006

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Re: Help Os 40 v max bad water leak
« Reply #13 on: May 31, 2007, 12:38:51 AM »

Have a look here and you might get lucky as OS do have some spares available for their older motors.

http://www.osengines.com/parts/xr15325.html

Always worth a try, they are listing con rods, which, I suspect, if you do not put some shims in, you are going to need... :'(


Glenn
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Martin [Admin]

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Re: Help Os 40 v max bad water leak
« Reply #14 on: May 31, 2007, 09:00:54 AM »


So does it run now with no water leaks?
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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #15 on: May 31, 2007, 12:46:07 PM »

I've not tried it yet Martin, the hylomar will probaly stop the  water leak ok.
Still deliberating if I also use it  as well where the missing gasket(head shim)  goes,
If it will compensate for the normal wear of an old engine, plus  increase in compression ratio.
Engine must have been running before like it because I had to clean off old fuel & gunge.
Also there are no signs of pitting on the head/combustion chamber,
 or burn marks on the liner from too high tempretures & pre ignition.
Undecided dazzle



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glennb2006

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Re: Help Os 40 v max bad water leak
« Reply #16 on: May 31, 2007, 01:40:25 PM »

I've not tried it yet Martin, the hylomar will probaly stop the  water leak ok.
Still deliberating if I also use it  as well where the missing gasket(head shim)  goes,
If it will compensate for the normal wear of an old engine, plus  increase in compression ratio.
Engine must have been running before like it because I had to clean off old fuel & gunge.
Also there are no signs of pitting on the head/combustion chamber,
 or burn marks on the liner from too high tempretures & pre ignition.
Undecided dazzle


Hi Bob,

on your drawing, the third item down is the shim. It goes between the head button and the cylinder liner.

Glenn




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dazzle

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Re: Help Os 40 v max bad water leak
« Reply #17 on: May 31, 2007, 02:15:42 PM »

Thanks Glenn,   re third item down, I  did know that, thats the bit I am undecided about.
In the early days skimming 30 thou off of a full size car head,  or fitting an 8 horsepower head in place of a 10
to raise compression would not be a problem, 
I'm just trying to relate  to useing the hylomar there, taking into account the wear on the engine,
plus the small tolerences involved, engine was run before like it,
also I will be using low nitro 10% not 20 or 30% etc. And  thanks for the parts list.

Cheers dazzle (bob)
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