Baaxter7484

My Feedback: (17)

Hey guy's, I was bout to begin another rebuild of my baja motor and let me tell you in the past I have had terrible luck with my rebuild's. Always ended up blowing shortly after every rebuild I did, well I figured it was due to the fact I did not torque the head bolt's properly. So thinking it was just the Chung Yang motor's I'd been getting I decided to spend a little more money and get a Zenoah, well it ran great at first then to my horror it did what all the others did and pushed the head gasket out. So here I am again I just figured this time I would not go it alone and get some advice first. I bought myself a small torque wrench and a copper head gasket, So my question to all you? What torque spec's you use for head bolts on a zenoah G26, and has anyone had so much trouble with their head gaskets blowing out? What could I do to prevent future gasket blowout's? and any advice on rebuilding the motor would be greatly appreciated.
Thank you!




Life is short, go drive an RC!!

willclark77

My Feedback: (2)

I had this happen before.  It's usually from the head bolts getting loose.  I cheat.  I drill two holes in the plastic cover over the head so I can tighten them without disassembling.  Snug em up after the first few times the engine warms then cools.  Once they set they'll stay.  I haven't blew a gasket since.

PBJT

I have the same problem, I rebuild em, nice clean table, all like I should and it works like crap...Give em to a friend, he rebuilds them in the dirt basically with no torqing and they last and last. I don't know what I have been doing wrong either, just one of those things.

Pete

mooman007uk

+1, same as that. they need retighening a couple of times or they tend to blow...if you have an inlb torquewrench then torque to 61inlb, go up progressively tightening both bolts. the holes in the fan cover make retighening a doddle

wolfie1

see you talk about retightening head bolts after it has been run and cooled, is this the same for new out of the box models? i do it with my nitros but am not sure about petrols

mooman007uk

yep, my theory is when it gets hot everything expands and this squishes the gasket a tiny bit more so when it cools it's not quite as thick so therefore the bolts will have essentially loosened a touch, a couple of checks after 10-15min runs and the gasket is squished to it's limit so then everything stays snugged up

mooman007uk

sorry double post, puter got a migrain

Baaxter7484

My Feedback: (17)

I plan to replace the junky stock blown gasket with a new stock spec DDM copper gasket, do the torque specs need to be the same?

Baaxter7484

My Feedback: (17)

Hey guy's Thank's for your input. Now when I rebuild the motor I will be doing it alot differently! And I will make sure to check the bolt's after I run it a bit, and retighten them as needed till they seat.





If my Baja offend's you, then maybe you should stay out it's way!

splcrazy

i have to rebuild my 5b engine again well not so rebuild , all i have to do is put on a new head gasket . for a long time ive been having problems with my 2 bolt head setup not sealing properly and i was using copper head gaskets , they would run great then i would get black oily sludge leaking out around the gasket , so i changed to the new DDM metal gasket they make and man they sealed up very nice and ran it about 5 times untill that gasket blew and popped out so that doesnt work either , so looks like i have to go back to using copper gaskets and just put up with leaking , i can never seem to get the head gasket to seal and be nice and dry when its running. i dont know it must be the fact that i run a high hp engine and the compression keeps blasting out the gaskets. lol never had this problem when it was running stock 23cc

Mudgy

has anyone tried the blue goo in a spray can - hylomar?
I used to use it on head gaskets for 4 stroke motors (1:1scale)
the fellas at toyota used to use paint as a head gasket goo..mind you these were old celicas with twin cam yamaha heads, so a rebuild was never far away.
I wonder if hylomar will aid a seal on a 2 stroker.....re torquing the bolts is a good idea..hysteresis will eventually stabilise in the metals; a bit like re tightening a drive belt or a conveyor chain for the 1st few weeks.........

kiyoung

Try a copper gasket with Locktite 5910.
Becareful, it will take up to 2 weeks to harden. However, if you warm up the engine, it will harden much quicker.
Check 5910 product data I attatched.

If you still have problem, try this parts.

http://www.rc-car-online-shop.de/cgi...0Tsuche7301/13

Or, somebody in US could make parts like those.
If you want to make the part, I think this one will be easier to make.
Check the last picture.


You have to make two 4mm holes in the crankcase.
The holes should go straight and tight. If a hole is too big, a bolt will be tilted.

A is about 3.5mm
B is about 4mm
c is about 8.7mm

Cheers

mooman007uk

if you use copper gaskets you have to anneal them first or they'll leak (good how to vid here[link]http://www.youtube.com/watch?v=3jSz11lz8MA[/link])..you also have to use gasket goo...I don't like them for 2 bolt heads at all because the torque is uneven with just 2 bolts in opposite corners and without the goo they wont seal...the goo toatlly defeats the purpose of a copper gasket anyhow...the copper is supposed to squish down onto the gasket surfaces and seal it and that's why it needs annealing so it's soft and malleable. (top fuel boys don't use goo on their head gaskets just annealed copper and their cylinder pressures are crazy)

the simplest and most effective way to seal heads is with an ungooed blue or green paper gasket (the black rubberised ones are poop) torque it properly and then retorque a couple of times after 10min cycles...if you don't retorque then it will leak every time guaranteed.

I have never had a 2 bolt leak after I bought a torque wrench and started using the above method...before that everyone would eventually blow

blue hylomar is probably the best sealant in the business, I've used it since my MX days 25yrs ago...back then it was good enough for the royal aircraft establishment and airforce in the UK so it must be good...don't even need gaskets with it for cases etc...thin smear on both surfaces and bolt together..never had a leak using the stuff

Baaxter7484

My Feedback: (17)

Well Since then I have learned a new way to stop all this fuss!! Buy a 4-bolt topend motor and THAT is what I plan to do!! I'm sick of this 2-bolt blow-out crap!! Next motor will be a 4-bolt topend for sure!!

Baaxter7484

My Feedback: (17)

Thank's I will try that as well. But I think in the end it's gonna be a 4-bolt topend for me

splcrazy

i'll have to try the copper annealing method when i pull this engine apart again, never knew i had to anneal the copper gasket before assembly , thats something ddm should mention in the description for them . i have tried gasket goo on copper gaskets but without the annealing and it still leaked , never heard of the blue hylomar stuff. but i do believe that the 2 bolt setup works good for like stock setups lol its when the mods go in these 2 bolts setups thats when the limits of what its desinged for starts to fail. I do think that the 4 bolt setup will instantly fix those problems aswell , my problem is that im running trevor simpson induction 2 bolt crankcase , i would have to buy all over again another TS crancase but in a 4 bolt and then a new 4 bolt 36mm cylinder head but thats easier said than done lol its so damn expensive, i want to just buy a 4 bolt topend and drill my own two other holes into the existing crankcase ive got , but i dont know if thats possible .

what would be awesome is if DDM put that special black coating like they are making for their new steel gaskets onto the copper gaskets . i dont know what kind of coating that black stuff is they are using on their steel gaskets but thats the best sealing dry running gasket i ever ran , the gasket itself is rubbish though lol as it just tore and blasted out .

Mudgy

no point goo'ing one of those..the heads can lift off the block at full noise


So the 4 bolt gasser head sleeves would bolt on resembling a nitro?
why didnt they do this to begin with?

kiyoung

If you have a normal engine,Loctite 243 is usually good enough.

First, clean the surface of head and crankcase. Becareful to remove any residue of oils on the surface.
Second, clean the inside of taps in the crankcase.
Third, put some loctite 272 on head clamping bolts.
Fourth,spread Loctite 243 on both side of Zenoah blue paper gasket.
Last, assemble the head.
You have to wait at least one day to start engine.

From my experience, this process work for most engines.

But, if you have tuned engine with high compression, somtimes it is not good enough.
Or, whatever unknown reason, if you still have problem of blown head gasket, then, you have to use Locktite 5910 or 4 bolt clamping as I explained at the previous post.

Also, most Europen engine tuners use Loctite 5910 or similar stuff not only for assembling head gasket, but also for assembling an insulator and carb.

Cheers.

mooman007uk

yep 4 bolts are the way to go but a 2 bolt can be sealed up without goop and not leak, on a flat surface gaskets should not need goo and when you torque a new gasket down it'll squish out 99.5% of the stuff anyhow, the bond is only as strong as the paper and if it aint torqued right it'll still blow

Gaskets are designed to compress and contort to the gasket surface and seal any very minor imperfections...if the surface is pitted or scratched then the goo comes into play to fill the small voids that the paper/copper can't squish into...

correct torque and re tightening is the secret to a leak free head gasket not goo
A decent inlb torque wrenche will run +$100 but saves an awful lot of frustration

Baaxter7484

My Feedback: (17)

Yea I got a nice torque wrench off the Bay, so now the next thing in the meantime is to anneal the copper. And try to get this 2-bolter to seal up for me. Thank's 4 that tip too!!