Blown headgasket: autopsy[pics]

Hey All.

Following up on my other thread on electrical gremlins, here:

http://xjbikes.com/Forums/viewtopic/t=25791.html

I suspected carb problems, but when even starting fluid wouldn't get it to fire(and with very healthy spark), i began to suspect something bigger was amiss. moving air on both exhaust and intake side made me think headgasket... We had trouble getting it to suck all the way down, but thought we got it in the end. i ordered a compression gauge last night to help diagnose it.

Talked with a mechanic at work today, and when i got home I sprayed soapy water on the seam... sure enough, bubbles. Tore it down(getting good at this lol) to find this:






What does that look like to you?

Incidentally, here's the bike as it sits, with the new front end. I think it looks pretty BA, not to mention the steering is a dream. I still need to make a bracket to hold the headlight/gauges on at the top(and about a hundred other things), but first things first.




-Joe

 

Ugh, that looks like fubar to me.

 

take all the studs out of the motor. and grab a straight edge. have the straight edge on its side sitting on the motor. CHECK ALL ANGLES for warpage. and check the head too.

SOMETHING made the head gasket go bad.

 

With that Gasket looking like it does, ... failing in the middle and burning-out through the Cam Chain Tunnel ...

You have to to Clean the Mating Surface of the Cylinder Head and "Straight-Edge Test" the Head for the possibility that the Head is warped.

The warp cannot be detected with the naked-eye.
The warp cannot be "Torqued-out'

Bring the Head to a Machine Shop.
Tell you suspect it's warped.
They'll tell you if it is and PLANE a few thousands off the whole surface to give you a perfectly flat surface that won't. ...

"Blow a Head Gasket"

 

Would have to agree with both snowwy and Rick, you NEED to determine what is warped on that engine. I'd also suggest you pull the jugs (you are going to check the block for warp right and you don't need to pull the studs, it slides right out with o-rings on the bottom to seal) and have them checked as well. New o-rings are in order and you will have the benefit of being able to really tell what went south on the upper end.

 

I've replaced leaky head gaskets but I've never seen anything like that on an air cooled bike, it takes a catastrophic failure to do that (i.e. severe overheating, the fact that only the inner cylinders failed supports the theory). Usually you see a gasket like that on a car where the coolant hasn't been changed in forever and actually rots out the gasket material (you don't have any crazy additives in your oil do you? :wink: ). I agree with the others, the head is unfortunately very likely warped. You may want to check the cylinders and rings as well while it's opened up. If it has overheated to the point of destroying the head gasket the cylinder/rings likely took a beating as well. On the upside, once machined, it will be good as new.

 

head gaskets on cars usually only give out when they are overheated. such as people with antifreeze leaks and running water but not keeping the level up. OR driving around with a closed thermostat.

some people are so poor that they can't even keep water in the car.

antifreeze now a days is designed to go 150k miles. it's called extended life antifreeze and comes in orange now. the chemical composition has lubrication qualities and running the green stuff can actually ruin the waterpump and motor.

 

actually there have been class action lawsuits against dex-cool (the orange stuff) and GM due to accelerated corrosion and gasket failure (Antifreeze Wiki). i've personally never had more problems with rads/heater cores than with a vehicle that has the orange crap in it. the funny part is GM's warranty stipulates the use of dex-cool. :roll:

 

the only motor to have a problem with head gaskets was the quad4. it couldn't take the abuse when people drove around with a bad thermostat or leaky waterpump. that motor was gm's worst nightmare.

the article your stating refers to intake manifold gaskets. on 2 particular engines. i wouldn't know about those problems as i've been retired from cars for 10 years now. those problems didn't exist when i left the field. so that's something fairly recent.

gm came out with the orange. but around here. the green disappeared some time ago. only thing we can buy around here is extended life.

 

Hello again,

Sorry for the delay, started full time work last week and had family in town over the weekend.

I got a new gasket kit, but I was thinking i ought to get to the bottom of this before i put it in.

I can get a set of feeler gauges and a (dead) straight edge tomorrow, but i'm thinking i ought to just take it to the machine shop tomorrow. should i take the cylinders too or just the head? anyone ever run into a warped cylider block? I really don't want to have to put the pistons back in.

Also, If anyone's very familiar with the seca turbo, I have a donor engine from a wrecked XJ650LJ available. I know the compression is lower, so i don't want to do a whole engine swap, and I don't want the turbo, but what differences are there specifically in the bottom end?

I am under the impression that the difference in compression is in the top end and I know the turbo has an oil cooler.

will keep you posted as progress happens.

--Joe

 

Throw straight edges all over the top of the jugs before you pull them; have the head checked FIRST and if it's warped and the jugs check ok in every imaginable direction then you will might be alright.

That being said, if you want to do it 100% RIGHT then yes, you need to pull the jugs and take them in too.

 

Now that I think about it... the turbo engine had many (4k vs 20k) fewer miles on it, i should just swap in the whole engine. the oil cooler is desirable to me, and I seem to remember reading somewhere that the turbo engine had some slightly beefed up parts, though it might have been the unsourced opinion here:

http://xjbikes.com/Forums/viewtopic/t=1287/

I know the turbo engine won't perform as well as the regular seca with its lower compression, but would the ratio be increased by using the (machined flat) heads from the naturally aspirated 650?

Also, i'd have to use the RJ carbs, i assume cams and TCI also should come from the naturally aspirated bike?