Blown head gasket

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Motogoon
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Blown head gasket

Postby Motogoon » Wed Dec 13, 2017 5:58 pm

So I've got a blown head gasket. Aaaaaaaargh

Last ride coolant blew out, temp was only on 4 bars. Bleed coolant system and refilled. Started with cap off and everything was fine until thermostat opened then coolant starts bubbling out, if I rev it it belches out all over the show.

This is the flippen 4th bike I've blown a head gasket on, I don't know what's with me and head gaskets!!

Anyway has anyone got any tricks for working out which cylinder it is without any specialized tools? The other bikes were inline four or single cylinder so no need to diagnose which one needed replacement.

There's no oil in the water and no water in the oil, looking at spark plugs doesn't seem to help as the coolant's not getting sucked in, just pressurized out.

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Re: Blown head gasket

Postby Colonel_Klinck » Wed Dec 13, 2017 7:45 pm

990 or 1290? If its a 990 its pretty easy. Even easier if it the front cylinder as you can do it without moving the engine.
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Re: Blown head gasket

Postby No. 47 » Wed Dec 13, 2017 8:21 pm

Are you sure it's the head gasket?
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Re: Blown head gasket

Postby Motogoon » Wed Dec 13, 2017 8:37 pm

2005 990, it just the amount of strip down I have to do that sucks! I could a single cylinder in a couple of hours. That's why I'm hoping its the front so less tear down, just need to find out how to diagnose whether its front or back.

Pretty sure its the head gasket. I chased the other 3 bikes all over the place but in the end I've never found any other scenario that blows coolant out the radiator cap directly related to revs. If you have any other suggestions to try though I'm all ears, I'd love for it not to be be a head gasket! I've never even heard of an LC8 blowing a head gasket, just my freakin luck.

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Re: Blown head gasket

Postby Colonel_Klinck » Wed Dec 13, 2017 9:15 pm

It sounds like the head gasket. If it is blowing bubbles out of the coolant, even more so when you rev it I'd say it is the head gasket.

Do you have a compression tester? If so whip both plugs out and test it on turn over. It might work better with bike hot and thermostat open. Or whip thermostat out.
"They lie about marijuana. Tell you pot-smoking makes you unmotivated. Lie! When you're high, you can do everything you normally do, just as well. You just realise that it's not worth the f*cking effort. There is a difference."
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Re: Blown head gasket

Postby Motogoon » Wed Dec 13, 2017 9:30 pm

No don't have a compression tester, was thinking maybe I could try somehow sealing a hose from the compressor on to the spark plug hole and see if bubbles come out the radiator. Good tip about the thermostat, I didn't even think about removing that before testing!

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Re: Blown head gasket

Postby Motogoon » Fri Dec 15, 2017 1:58 am

So I reckon I'm just gonna replace both head gaskets while the bike is stripped down, the rear has a slightly leaking base gasket anyway so I'll do base and head gaskets.

I'll have to order everything I need in one go because ktm New Zealand won't have anything in stock if I'm halfway through and forgotten something!

Let me know if I've missed anything obvious

2 x base gaskets
2 x head gaskets
8 x stronger studs (is there a little one that needs upgrading also?)
2 x copper washers for cam chain tensioners
2 x piston circlips
Do I need new head bolts/washers?

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Re: Blown head gasket

Postby Aphex » Fri Dec 15, 2017 3:15 am

Motogoon wrote:So I reckon I'm just gonna replace both head gaskets while the bike is stripped down, the rear has a slightly leaking base gasket anyway so I'll do base and head gaskets.

I'll have to order everything I need in one go because ktm New Zealand won't have anything in stock if I'm halfway through and forgotten something!

Let me know if I've missed anything obvious

2 x base gaskets
2 x head gaskets
8 x stronger studs (is there a little one that needs upgrading also?)
2 x copper washers for cam chain tensioners
2 x piston circlips
Do I need new head bolts/washers?



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Re: Blown head gasket

Postby Colonel_Klinck » Fri Dec 15, 2017 9:18 am

Just glanced through that walk through. Damn I wouldn't fancy doing that again. Especially as the bloody thing dropped a valve 350 miles later and destroyed the rear cylinder, piston and head :cry: Still lesson learned, at 52k miles the valves were probably due to be changed and I was cheap and didn't change them.
"They lie about marijuana. Tell you pot-smoking makes you unmotivated. Lie! When you're high, you can do everything you normally do, just as well. You just realise that it's not worth the f*cking effort. There is a difference."
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Re: Blown head gasket

Postby RichUK » Fri Dec 15, 2017 10:48 am

Just a thought but will the engine start/run with just 1 spark plug in?

If so pull one plug out and run the engine with the rad cap off, if you don't get bubbles it's likely is that one.

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Re: Blown head gasket

Postby Motogoon » Fri Dec 15, 2017 6:47 pm

Colonel_Klinck wrote:Just glanced through that walk through. Damn I wouldn't fancy doing that again. Especially as the bloody thing dropped a valve 350 miles later and destroyed the rear cylinder, piston and head :cry: Still lesson learned, at 52k miles the valves were probably due to be changed and I was cheap and didn't change them.


Gutted! Yeah I have read that a few times, very useful but at the same time it shows how daunting it is. I've rebuilt a few supermoto's and dirt bikes and they're sooo easy, tank off and you're ready to go.

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Re: Blown head gasket

Postby Motogoon » Fri Dec 15, 2017 6:49 pm

RichUK wrote:Just a thought but will the engine start/run with just 1 spark plug in?

If so pull one plug out and run the engine with the rad cap off, if you don't get bubbles it's likely is that one.


That's an idea, anyone know if it will run with a plug out, will gas spray out? I'd have to have it hot enough for the thermostat to be open also. Starting to sound a bit dodgy!

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Re: Blown head gasket

Postby No. 47 » Fri Dec 15, 2017 7:32 pm

Run engine up to temperature, disconnect each coil pack and run engine in turn.
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Re: Blown head gasket

Postby Colonel_Klinck » Fri Dec 15, 2017 9:11 pm

It won't run on one cylinder. Without a compression tester you are going to struggle to find out with cylinder it is. Even with one it might not be down by a large amount. You will probably need to remove the thermostat as well as I'm guessing it opens somewhere around 80c. It won't take long for the coolant temp to drop back down and the thermostat to close. As you'll be turning the engine over coolant will continue to circulate through the rad cooling it.
If I was you I'd just bite the bullet, whip the engine out and change both. You have to change the base gaskets as well as the cylinder is held in place by the same bolts that hold the head on. It isn't that difficult. That walkthrough was way more complicated as I was changing the timing chains as well. Just make sure you have the engine in TDC for each cylinder when you remove the cams and put them back. Oh and either buy or make yourself a locking bolt. I can't remember what the bolt size is now, just needs grinding to a point on the end you insert into the engine.
"They lie about marijuana. Tell you pot-smoking makes you unmotivated. Lie! When you're high, you can do everything you normally do, just as well. You just realise that it's not worth the f*cking effort. There is a difference."
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Re: Blown head gasket

Postby No. 47 » Fri Dec 15, 2017 9:26 pm

Both of mine have run, reluctantly, on one.
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Re: Blown head gasket

Postby Motogoon » Fri Dec 15, 2017 9:32 pm

Colonel_Klinck wrote:It won't run on one cylinder. Without a compression tester you are going to struggle to find out with cylinder it is. Even with one it might not be down by a large amount. You will probably need to remove the thermostat as well as I'm guessing it opens somewhere around 80c. It won't take long for the coolant temp to drop back down and the thermostat to close. As you'll be turning the engine over coolant will continue to circulate through the rad cooling it.
If I was you I'd just bite the bullet, whip the engine out and change both. You have to change the base gaskets as well as the cylinder is held in place by the same bolts that hold the head on. It isn't that difficult. That walkthrough was way more complicated as I was changing the timing chains as well. Just make sure you have the engine in TDC for each cylinder when you remove the cams and put them back. Oh and either buy or make yourself a locking bolt. I can't remember what the bolt size is now, just needs grinding to a point on the end you insert into the engine.


Yep you're right, I will just do both instead of trying trying to find ways to weasel out of a full strip down!

Ah yes the lock bolt, I forgot about that. On single cylinder bikes I just used to take the power bar that was on the flywheel nut and zip-tie it to the footpeg so the engine couldn't move.

Suppose I need exhaust gaskets too

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Re: Blown head gasket

Postby Colonel_Klinck » Fri Dec 15, 2017 10:39 pm

Motogoon wrote:
Colonel_Klinck wrote:It won't run on one cylinder. Without a compression tester you are going to struggle to find out with cylinder it is. Even with one it might not be down by a large amount. You will probably need to remove the thermostat as well as I'm guessing it opens somewhere around 80c. It won't take long for the coolant temp to drop back down and the thermostat to close. As you'll be turning the engine over coolant will continue to circulate through the rad cooling it.
If I was you I'd just bite the bullet, whip the engine out and change both. You have to change the base gaskets as well as the cylinder is held in place by the same bolts that hold the head on. It isn't that difficult. That walkthrough was way more complicated as I was changing the timing chains as well. Just make sure you have the engine in TDC for each cylinder when you remove the cams and put them back. Oh and either buy or make yourself a locking bolt. I can't remember what the bolt size is now, just needs grinding to a point on the end you insert into the engine.


Yep you're right, I will just do both instead of trying trying to find ways to weasel out of a full strip down!

Ah yes the lock bolt, I forgot about that. On single cylinder bikes I just used to take the power bar that was on the flywheel nut and zip-tie it to the footpeg so the engine couldn't move.

Suppose I need exhaust gaskets too


You will be unlucky if they disintegrate. I would buy the rubber cam cover gaskets though. You'll be gutted if you put it back together only to find one leaks. Check the valve clearances while you're at it. Harley Davidson shims fit and come in far more sizes. Download this shim excel doc. Works it all out for you https://www.dropbox.com/s/kqorujpuuk9s7 ... s.xls?dl=0
"They lie about marijuana. Tell you pot-smoking makes you unmotivated. Lie! When you're high, you can do everything you normally do, just as well. You just realise that it's not worth the f*cking effort. There is a difference."
The late Bill Hicks

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Re: Blown head gasket

Postby DaveNZ » Sat Dec 16, 2017 3:51 am

Motogoon wrote:So I reckon I'm just gonna replace both head gaskets while the bike is stripped down, the rear has a slightly leaking base gasket anyway so I'll do base and head gaskets.

I'll have to order everything I need in one go because ktm New Zealand won't have anything in stock if I'm halfway through and forgotten something!

Let me know if I've missed anything obvious

2 x base gaskets
2 x head gaskets
8 x stronger studs (is there a little one that needs upgrading also?)
2 x copper washers for cam chain tensioners
2 x piston circlips
Do I need new head bolts/washers?

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