Author Topic: Blown Head Gasket On My Trailblazer  (Read 11376 times)

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High On Octane

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on: May 20, 2013, 06:31:12 am
So after hearing my head gasket blow while out on a ride this morning I decided to not waste time and to tear the heads off tonight.  Sure enough, the right cylinder had completely blown out about a 1/4" section of gasket towards the inner side of the cylinder.  Upon examination, I also found that that gasket was leaking slightly on the left cylinder but the gasket was in tact.

I also inspected the piston tops, some carbon build up but no sign of damage, pre-ignition or lean conditions.  The cylinders themselves looked absolutely amazing.  I'm not sure if the pistons were replaced or not, but they were at least definitely re-ringed and cylinders professionally honed.  No scoring what so ever, in fact, you can still see all the the brush marks on the cylinder walls from when it was machined.

So, it looks like I got off lucky and just need to replace the head gaskets and other associated gaskets.  I'll be placing an order with Hitchcock's tomorrow morning and hopefully have the parts by the end of the week.

Does anyone know the torque specs for the head bolts?

Scottie


Blown Gasket


Left Head


Right Head


Piston Tops


Cylinder Walls
2001 Harley Davidson Road King


ace.cafe

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Reply #1 on: May 20, 2013, 11:20:07 am
I'd recommend checking the cylinder and head mating surfaces in that area for flatness. Or for any other reason that the gasket blew right there.
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ERC

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Reply #2 on: May 20, 2013, 01:32:58 pm
The heads look like it was redone with very few miles on them. Ace is right about checking flatness. Also get the composite gaskets. I've been torqueing mine to 20ft.lbs if I remember correctly.  ERC
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High On Octane

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Reply #3 on: May 20, 2013, 01:55:01 pm
Should I use l like the edge of a metal ruler to check for flatness?  Also I planned on getting the composite gaskets, they aren't that much more.  And I agree, I think someone has already been through this motor at some point.  Possibly the motor was rebuilt and the msg failed very shortly afterwards.  Also as far as that right gasket blowing out. It very well may have been that the head wasn't torqued properly.  The head nut by the spark plug was incorrect and also the head on 1 of the long head nuts on that cylinder has been "shaved down" to the next smaller hex size. I ordered replacements for those as well.  And the head bolts on the right cylinder weren't nearly as tight as the head bolts on the left cylinder.  This may have been a case of the bolts loosening up just enough for it to cause a problem.

Scottie
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ERC

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Reply #4 on: May 20, 2013, 02:09:28 pm
It could be the bolts were never re torqued after it was done. Your best bet to check flatness on the heads is to get a sheet of 1/4" plate glass and tape a piece of 220 grit paper to it to see where it touches the head when swirled around on the sand paper. Other than that take it to a machine shop.  ERC
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High On Octane

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Reply #5 on: May 20, 2013, 07:16:11 pm
Good news.  I just got off the phone with my local head pro and he's going to jet blast my heads for $10.  Score!!!  I'll have him take a quick peek at the mating surface and make sure it's flat and true.

Scottie
2001 Harley Davidson Road King


ace.cafe

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Reply #6 on: May 20, 2013, 08:12:56 pm
Good news.  I just got off the phone with my local head pro and he's going to jet blast my heads for $10.  Score!!!  I'll have him take a quick peek at the mating surface and make sure it's flat and true.

Scottie

Be careful that he doesn't knock off any fins with that high pressure blast. The fins break off pretty easy on these things.
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Reply #7 on: May 21, 2013, 02:03:48 pm
I recently rebuilt an early 700 Meteor [1953]. About 800 miles after the rebuild, the left head gasket blew at the innermost part, facing the other cylinder. The other head gasket was also going downhill, due to the heat / flame that was escaping past the blown one. Dark areas on the cylinder heads' gasket faces bore witness to a slight distortion of the gasket faces at this area of the heads - a hot spot where each head is right next to its' neighbour.
 I placed some fine emery on a known flat surface and refaced the gasket areas of the heads.
 Next came a bonus - I asked, assuming they were available, for solid copper head gaskets - the blown ones had been the copper 'sandwhich' type and they can blow quite easily at times. Solid copper gaskets came, but would not fit. It turned out there were no solid gaskets for the 700 twins, only the 500 Meteor Minor and this is what I had been sent. I had to enlarge the cylinder holes in them, to make them pass over the cylinder spigots [the M.M. 500 has no spigots] and file out the pushrod holes a little and then they fitted. Job done and I doubt it will have any problems with head gaskets again.
 That central area, where the two heads meet is a weak and 'hot spot' area, needing special attention. As for torque figures for the head nuts, just tighten them equally and don't overdo it, two of them are only accessible with a spanner anyway.
 B.W.
« Last Edit: May 21, 2013, 06:21:36 pm by Bullet Whisperer »


ERC

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Reply #8 on: May 21, 2013, 05:54:53 pm
I'm suprised you couldn't get the solid copper. Won't the later solid copper ones fit? I know they're a different #. Haven't had one that old apart to know.  ERC
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High On Octane

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Reply #9 on: May 21, 2013, 10:28:08 pm
Well, I have great news!  I picked up my heads this morning from Heads By Drew after having them degreased and we took a look at the decks together.  On both of the heads there was a little bit of warpage in the area where the 2 heads meet.  You know, where it has known problems.  Drew didn't have a jig to mount the heads to a mill machine, but he did have a bad ass industrial belt sander.  He asked if I wanted him to give the heads a try on the belt sander.  Given his excellent reputation in the Denver Metro, I figured why not, there's obviously a problem there.  After great finessing on the belt sander, he was able to remove about .001 off of each head and get them true again.  And he only charged me $30 to clean and true them!

Left Cylinder After


Right Cylinder After


After that I stopped and picked up some new wire brush wheels to clean the piston tops and combustion chambers.  After cleaning the piston tops I made an interesting discovery.  Brand new pistons stamped +040!  So the top end has definitely been apart on this bike, and most importantly, that means I have a 750!  Also, when I do the full build this winter, I won't have to bore the cylinders for the high compression pistons.  After cleaning the pistons, I decided to clean up the cylinder decks.  I pulled all the head studs dropped the pistons and filled the cylinders with rags, and took my really nice sanding block and some 220 paper and carefully sanded the cylinders decks.  They appeared to be in good shape and didn't require a lot of attention, but I finished them off with my flat sharpening stone.  I decided I'm going to replace the 4 heads studs on the inner portion of the head/cylinder.  Can't hurt, right?!  Now all I need is parts.    :D

Scottie



2001 Harley Davidson Road King


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Reply #10 on: May 21, 2013, 11:14:40 pm
Looking nice and clean there, Scottie. BTW, you probably have approx. 715 cc there, the [736cc] 750's ran a 93 mm stroke as well as a 71 mm bore.
 B.W.


High On Octane

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Reply #11 on: May 22, 2013, 01:57:13 am
Looking nice and clean there, Scottie. BTW, you probably have approx. 715 cc there, the [736cc] 750's ran a 93 mm stroke as well as a 71 mm bore.
 B.W.

I didn't realize the Interceptors had a longer stroke.  As if it wasn't long enough.    ;D  Either way, it's refreshing to see the cylinders/pistons in brand new excellent shape.  I'm also excited that the heads came out so good with minimal effort.

Just placed my order through Hitchcocks, so hopefully I can get the top end thrown back together early next week.

Scottie
2001 Harley Davidson Road King


ace.cafe

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Reply #12 on: May 22, 2013, 02:07:31 am
Looks like you saved some money on the build!

Always a nice surprise!
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rotorwrench

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Reply #13 on: May 22, 2013, 07:51:23 pm
The 692cc (700) had 5/16 studs to hold the heads & barrels down. George Helms and several other racers used to replace the 5/16" studs with the 736cc (750) studs that were 3/8" diameter. He also used the Interceptor tube nuts to hold everything together but the 700 tube nuts can also be modified to fit 3/8" if necessary. Blown head gaskets have always been a problem on the RE big twins. It would have been less a problem if they had made castings in one piece for the twin cylinders instead of separate castings. The parts started out 500cc then ended up 692cc with high compression pistons and cams to boot so the original design was pushed to the limits of power output. The 736cc Interceptor stuff was the strongest of all the RE big twins. For folks that just put around town, it's usually not a problem but racing is a different story alltogether.

When I surface my heads, I put sheets of silicon carbide paper on a surface plate with a bit of oil and lap the heads till the warpage is just gone. I don't trust too many machines on those little castings plus I only remove just what is needed to get the job done and no more.
« Last Edit: May 22, 2013, 07:55:42 pm by rotorwrench »


High On Octane

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Reply #14 on: May 22, 2013, 08:02:08 pm
The 692cc (700) had 5/16 studs to hold the heads & barrels down. George Helms and several other racers used to replace the 5/16" studs with the 736cc (750) studs that were 3/8" diameter. He also used the Interceptor tube nuts to hold everything together but the 700 tube nuts can also be modified to fit 3/8" if necessary. Blown head gaskets have always been a problem on the RE big twins. It would have been less a problem if they had made castings in one piece for the twin cylinders instead of separate castings. The parts started out 500cc then ended up 692cc with high compression pistons and cams to boot so the original design was pushed to the limits of power output. The 736cc Interceptor stuff was the strongest of all the RE big twins. For folks that just put around town, it's usually not a problem but racing is a different story alltogether.

When I surface my heads, I put sheets of silicon carbide paper on a surface plate with a bit of oil and lap the heads till the warpage is just gone. I don't trust too many machines on those little castings plus I only remove just what is needed to get the job done and no more.

Thanks for that information rotorwrench.  I do in fact plan on doing a performance build over the winter and installing the 8:1 compression pistons and lightened connecting rods and Constellation cams, so I will definitely make sure to modify the block to accept the 3/8" head studs.  Now where the hell do I get a tap for the British threads?  Also, is there any modifications that need to be done to the head to accept the bigger studs?  I'm assuming I'll need to drill out the mounting flange.

And my order shipped from Hitchcocks today so, YAY!

Scottie
2001 Harley Davidson Road King


ERC

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Reply #15 on: May 22, 2013, 11:18:33 pm
You can buy all the British tap and die stuff from Hitchcocks.  ERC
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High On Octane

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Reply #16 on: May 26, 2013, 03:18:45 pm
I hate the waiting game.  I have a 3 day holiday weekend starting today, and my bike sits, with parts in boxes, as I wait for other parts to arrive.    :(   With any luck, maybe they'll show up Tuesday and I can at least get the bike back together to ride on Wednesday. 

Scottie
2001 Harley Davidson Road King


ERC

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Reply #17 on: May 26, 2013, 04:48:16 pm
Hi Scottie, Did they ship them with tracking? Another thing on the taps and Dies you can get them British Tools and Fasteners www.britishfasteners.com he's in Lyons N.Y. He also has a lot of British nuts bolts etc.  ERC
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High On Octane

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Reply #18 on: May 26, 2013, 05:31:22 pm
Hi Scottie, Did they ship them with tracking? Another thing on the taps and Dies you can get them British Tools and Fasteners www.britishfasteners.com he's in Lyons N.Y. He also has a lot of British nuts bolts etc.  ERC

No, unfortunately they did not ship with tracking.  I do know that all I ordered was head gaskets, 2 sets of intake gaskets, 4 head bolts, a few nuts and washers and the exhaust tie rod (the 2 right nuts ((that sounds like a punk rock band lol)) seized on mine and it snapped during dis assembly).   So it can't be in too big of a package and can't weigh much.  Although that doesn't mean anything when you're talking over seas shipping.

I'm just bummed that I almost had the bike dialed in, then BAM!  I have to be honest, it scared the shit out of me when that gasket blew because I was on the throttle hard.  My immediate thought was "Shit!  I just spun a bearing!" but then I realized that it wasn't a "clanking" sound but a "popping".  So I pulled over and looked and was relieved to see the smoke coming out of the head/cylinder seam, because that's an easy fix.  Just would've been nice to get out for a ride on the holiday.  You know, to enjoy myself.  And smile ear to ear every time I make a Hardley Ableson owner jealous.    ;D

Scottie
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High On Octane

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Reply #19 on: May 30, 2013, 12:57:10 am
WHERE THE EFF ARE MY PARTS HITCHCOCKS?!?!?!
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D the D

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Reply #20 on: May 30, 2013, 03:45:36 am
Probably sitting in NY or NJ with mine.
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High On Octane

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Reply #21 on: June 04, 2013, 03:21:15 pm
Not too excited at the moment, even a little leery.  FINALLY got my parts from Hitchcocks and the head bolts do NOT match what I pulled off the bike.  It appears someone has replaced the stock 5/16" head bolts with what appears to be 3/8" diameter of a different style stud.  The head bolts I pulled off have a short section of course threads that screw into the block and then the entire length of the rest of the bolt has fine threads.  I'm about to run down to Ace Hardware and see if the threads happen to be metric or SAE.    :(

Scottie
2001 Harley Davidson Road King


ERC

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Reply #22 on: June 04, 2013, 05:42:14 pm
The later Interceptor studs were 3/8" and sometimes people will go to the bigger stud for strength. They may have used them. Tough part is they're a British thread. ERC
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High On Octane

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Reply #23 on: June 05, 2013, 12:53:37 am
Got the bike put back together.  Turns out the head bolts are SAE 3/8".  I'm guessing they are probably for a Harley, but who knows.  It's running really good but seems pretty noisy at the top of the motor.   Not really sure what the deal is, but it did quiet down some after I ran it around the block.  Anyways, took it down the road and it definitely has a little more torque with the new head gaskets and is firing on the first kick.  Definitely a little more compression noticed in the kicker.

How much valve noise do these old twins make?  I noticed chatter before, perhaps it just stuck out more noticeably until the oil got back to the valves?

Scottie
2001 Harley Davidson Road King


Arizoni

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Reply #24 on: June 05, 2013, 01:47:59 am
You probably should take it pretty easy until the engine has gone thru a few thermal cycles and the head is retorqued.
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High On Octane

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Reply #25 on: June 05, 2013, 03:36:40 am
I was taking it easy.  I only got on it once and that was rolling from 4th at about 45mph.  I'm thinking it was just so noisy at first because it was starving for oil.  I'm going to ride it.  At this point, if I have to tear it down again I'm tearing it ALL the way down.  I just need the damn thing to get me thru the summer/fall.  And come to think about it, I almost always wear a helmet, and the few times that I haven't worn a helmet I remember thinking it was noisy then too.

Scottie
2001 Harley Davidson Road King


Bullet Whisperer

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Reply #26 on: June 05, 2013, 09:10:31 am
The valve 'clearences' for these machines is supposed to be 'nil', but I usually go for a tiny clearance - say 0.002", just to be safe. More than this will result in more top end noise, also, if the timing chain is too slack, the engine will clatter like a bag of spanners. Excessive end float on the camshafts will also cause noise.


High On Octane

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Reply #27 on: June 05, 2013, 01:49:32 pm
I set the valve lash at .012 which is what the repair manual says the specs are supposed to be.  I thought it seemed a little on the fat side, but .002 seems like it would be too tight.

ERC - What are you seeing your valve lash at?

Scottie
2001 Harley Davidson Road King


ERC

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Reply #28 on: June 05, 2013, 02:46:43 pm
Scottie, I set them at no clearance with the engine cold. Definitely no more than .002. Also if you've gotten it hot retighten the head bolts while your doing it.  ERC
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High On Octane

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Reply #29 on: June 05, 2013, 03:44:32 pm
That must be all the chatter I hear then.  The lifters are too sloppy and slapping around.  I'll readjust them today sometime.  Thanks guys.

Scottie
2001 Harley Davidson Road King


rotorwrench

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Reply #30 on: June 06, 2013, 12:28:45 am
With seperate cylinders, they grow near .010" to .012" when fully warmed up. That is why the old engine specs mention to set them cold at nil. They mention nil to .005" on the exhausts but .002" should be OK for all of them just to insure you don't have any valves open when cold starting.


High On Octane

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Reply #31 on: June 06, 2013, 01:26:16 am
I set the valves by ear and with a .004 gauge.  I set them to where I could just barely pull the .004 feeler thru, then tightened until I just barely got a tick when wiggling the rocker arm.  The bike sound and runs the best it ever has.  Thanks again guys!

Scottie

2001 Harley Davidson Road King