Blown head-gasket [hi-res dirty pics] What to do now?

[FlyingDutchMan]

This engine is the first one from my trusty CBR250R (MC19) - it is currently running my backup engine.

Well I've attached the photos of the problem. It seems to have blown through on cylinder #4 - the one on the left. The head looks okay, but the close up of the engine block should reveal the real problem - the block has been corroded/pitted quite badly. While this isn't the bore itself, I'm still pretty sure that its going to cause problems if I leave it as is. Any opinions on how to fix up that problem.

It looks like the last person to take the head off was an utter clutz and used some silicon gasket sealer when they put it back together ... which is hopefully the cause of the problem, rather than a warped head.

2nd lot of problems: With head bolts. One would not loosen at all (broke 3 sockets and rounded another trying) when trying to remove the head and one loosened far too easily. In the end I drilled the head off the stuck one. Any advice on how to remove a headless stuck bolt (see pic #3)? The other bolt which was too loose seemed to have removed the thread from the hole and taken it with it when it came out. I assume that this can be fixed by helicoil/recoil kit. Has anyone had experience doing this? Recommend taking to a shop to get it done?

[FilthyLuka]

fuck me! talk about uber loctite... i need to get me some of that shit!

get a straight edge and check the head for warpage by using a set of feeler gauges. a helicoil is gonna be neccesary for the head. scrape of the old gasket and see if the corrosion like substance is actually part of the head or a alien substance thats just sittin there, could be silicone that got burnt due to engine temperature? if the dudes stupid enough to use silicone for a head gasket, hes probably stupid enough to use the WRONG silicone.

if the heads warped you'll need to have it plained and shimmed, if ya cant find a shim, i have a dodgy trick you could try but we'll talk about that later...

denis

[Sketchy_Racer]

oh... the story i know all to well.

Start by cleaning the mating surfaces. Completly clean. NO crap at all. Like polish finish.

Then check both head and Barrels for warp. cant remember the tolerances off the top of my head.

Order a brand new head gasket NOW. they took ages for my one.

DO NOT pull the valves out if you can help it. replacing the valve stem seals is not cheap. at all

If there is any pitting around the head/barrel, find out what caused it

It could just be a casting imperfection

keep us upto date with things.

-Glen

[FlyingDutchMan]

Checked out the blackish goo - it is just that - I can rub it off with my fingers so I'm very sure its crappy silicon gasket seal.

Already have a new head gasket - I went into the shop and collected it straight away... very fast service... at a large markup (~$40) if my glance at the computer screen was right.

The pitting I'm pretty sure is the Al alloy being corroded by hot exhaust gases over a long period (few thousand k's). The barrel itself is fine (presumably some cast iron alloy).

Will check the head and barrels for the tolerances tomorrow. Have the manual, a metal straight edge and feeler gauges so I can do easy enough. I suspect that the max is tolerance is 0.02mm (less than a thin layer of silicon gasket goo) if my memory serves me right.

[Sketchy_Racer]

Dont tell anyone you heard this from me.

But i am a rough bugger, and on engines like that with damaged cases, i have used kneed it or any other similar metal epoxy.

It bonds well with a clean surface, and once machined down, has never leaked!!

BUT, i dunno you would get away with that there.


Yeah barrel will be cast iron. None of this Electro plated crap there.

good luck!!

[FilthyLuka]

ah! for removing that headless bolt. drill a hole in the middle, get the biggest fuck off stud extractor you can from repco and screw that into the newly drilled hole. Now go and put your man crescent (huge arse crescent) on the stud extractor and turn! add bars or levers to your man crescent if you need extra leverage...

as for the helicoil, i have absoulutely (sp) no idea how to install those... im sure someone on KB knows how to get helicoils puts in...

[scumdog]

To remove the broken bolt: get a nut that is as close to the dia. of the stud internally, slide it over said stud then get a handy mate (you DO have a handy mate?) to weld the nut to the stud - then you can use a spanner again.

If that doesn't work and for better effect cut the head off a big-arse bolt, drill a hole through the middle of it to the correct size and do as above - at least THIS TIME you'll be able to use a larger socket/spanner

[nadroj]

When removing the stud heat the area around the stud but try to avoid heating the stud itself. The alloy will expand quicker than the stud thereby making it easier.

[bumsex]

yes but be careful when you apply the heat as too much in one area is no good.

[FlyingDutchMan]

To remove the broken bolt: get a nut that is as close to the dia. of the stud internally, slide it over said stud then get a handy mate (you DO have a handy mate?) to weld the nut to the stud - then you can use a spanner again.

If that doesn't work and for better effect cut the head off a big-arse bolt, drill a hole through the middle of it to the correct size and do as above - at least THIS TIME you'll be able to use a larger socket/spanner

Best idea I've heard yet. I've got access to a welder and a good supply of sacrificial nuts so it should get done easy enough.

[Richard Mc F]

when battling the stuck stud .....belt the fucker....one or two good sharp taps on the end of it, helps break corrosive bonding....heat, yeah but let it cool down or may need 2 helicoil/recoils, and as for them, if you can tap a thread, you can use one...... otherwise engine reconditioner, enginneering shop, bike shop ( motorcycle repair type I would think) cause if you stuff it up it just gets more interesting, not impossible but interesting.

The epoxy/metal stuff is ok around cooling and oil passages but not around the combustion chamber sealing area ( top of the liner) silicone sucks ass, so do a lot of other traditional gasket compounds ( hylomar does have its place though)use loctite 515 master gasket or sicomet ( german equivalent) ...pm me if you are having trouble

[Bonez]

To remove a stuborn broken stud one can spray Wd40 or CRC 5.56 around the thread, allow time to soak, give some hefty taps with hammer as suggested above, lock a heavy pair of visegrips firmly on the stud (and I mean firmly). Tap the visegrips with the hammer. Remove stud.

It should be noted some studs are held in with a locking compound.

[Ivan]

Heli coil is easy.


You drill the hole out to the size of the drill bit that comes with the kit then tap a thread in there,
Then use the tool to insert the helicoil it will go overthe thread andmake it the size you choose

[FlyingDutchMan]

Well now that I've had time to have another go at it, I'd decided to try the easy route first. So I got the electric drill, opened the chuck right up, put it over the top of the bolt and wound it up. Got it as tight as the drill would go, put it in reverse and the bolt came out in a record 0.3 seconds.

Now just to source another bolt (I'll bet Honda charges $30 for one!) and carefully re-assemble.

[scumdog]

Well now that I've had time to have another go at it, I'd decided to try the easy route first. So I got the electric drill, opened the chuck right up, put it over the top of the bolt and wound it up. Got it as tight as the drill would go, put it in reverse and the bolt came out in a record 0.3 seconds.

Now just to source another bolt (I'll bet Honda charges $30 for one!) and carefully re-assemble.

Plurry-hell!
You were lucky, the stud can't have been in that tight after all, I wouldn't count on using that trick too often!