Author Topic: 836 head gasket exhaust leak and loose head bolts after rebuild (Read 7509 times)

brandEn · « **on:** April 29, 2011, 04:29:26 PM »

So after all the time, effort, and money rebuilding my CB750 project I had my first major issue. I went for the first start and it was running like major #$%*. I figured timing or carb issue. So after checking and then rechecking everything I noticed when I would crank it over I had some smoke coming from the header area. I figured exhaust leak. So I replaced the copper header gaskets. Got her running had the same problem. I started looking around with my flashlight and...oh crap. I could see the head gasket seam bubbling up the cleaning fluid that I just sprayed around the area. So I accepted my fate and tore down the top of the motor (with the help of tweakin, thanks bro!). Upon tear down the head nuts and bolt were way to loose. The thing is, when we assembled everything was torqued to spec. Has anyone ever had this happen to them? Thoughts?

bear · « **Reply #1 on:** April 29, 2011, 05:10:42 PM »

Stripped stud bolt thread crankcase?

Cheers,
Brian

brandEn · « **Reply #2 on:** April 29, 2011, 05:43:41 PM »

All the new HD studs and threads are good. Checked all the studs into the crankcase and those stayed tight. I guess all the nuts on the head side just decided to loosen up.

mick7504 · « **Reply #3 on:** April 29, 2011, 06:18:03 PM »

A new set of head nuts might be worth considering.
The threads on the old nuts could be stretched a bit from being retorqued several times in the past and now not maintaining their correct torque values.
Just a thought.
Mick

brandEn · « **Reply #4 on:** April 29, 2011, 06:22:01 PM »

I replaced with new nuts as well. I was wondering, do they need loctite?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #5 on:** April 29, 2011, 06:34:07 PM »

Shouldn't need loctite. Some of the guys torque in sequence then let it sit for a day and go back and retorque.

MRieck · « **Reply #6 on:** April 29, 2011, 07:36:29 PM »

Did you lube the cylinder stud threads? Make sure the oil drain back dowels aren't to long not allowing the cylinder head to pull down enough. Also ...you asked me about CR carb manifolds for the F2. If memory serves correct you need the DOHC manifolds which probably accounts for the 220.00 figure you said for the right pieces. That is unless you find an old set of CR SOHC manifolds which where to big for the K (they did work with big cursing). They were long also.

brandEn · « **Reply #7 on:** April 29, 2011, 08:19:56 PM »

Thanks Mike, I will check the dowels when I install the new gasket. As for the carbs I ended up using early intake rubbers and they seem to work fine.

Can you recall what length the dowels need to be?

Doctor_D · « **Reply #8 on:** April 30, 2011, 06:59:52 AM »

Mine loosened up because I was getting bogus torque readings when I tightened the studs and other head bolts. When I pulled the engine apart and ran a tap down the stud threads in the cases, it pulled out so much garbage.

Nothing like a trial run engine build...

Magpie · « **Reply #9 on:** April 30, 2011, 07:45:46 AM »

I was having trouble torquing my head bolts on my last rebuild and mentioned it to an friend that's worked on the bikes for years. He said a trick he learned was to use two washers under the head nuts. It worked for me although that engine doesn't have much running time the gasket seems to be fine. Maybe you're running out of threads on the studs and the nuts are bottoming and giving false readings. Did you plane the head or barrels? Thinner gaskets?
Cliff.

brandEn · « **Reply #10 on:** April 30, 2011, 08:35:06 AM »

Cycle X did deck the surfaces when they did my head and bore job. I don't know how much they removed but it doesn't look like much. The gasket I used is thin and more than likely most of the problem. I made sure the threads in the case were cleaned out and I dipped the studs in engine oil before install. I ordered a new Cometic gasket so hopefully that will take care of my issue. I thought about the double washer thing, I was thinking maybe one of the regular washers along with a lock washer. I don't want to screw anything up though. So if this is a bad idea let me know!

MRieck · « **Reply #11 on:** April 30, 2011, 10:57:04 AM »

Quote from: brandEn on April 30, 2011, 08:35:06 AM

Cycle X did deck the surfaces when they did my head and bore job. I don't know how much they removed but it doesn't look like much. The gasket I used is thin and more than likely most of the problem. I made sure the threads in the case were cleaned out and I dipped the studs in engine oil before install. I ordered a new Cometic gasket so hopefully that will take care of my issue. I thought about the double washer thing, I was thinking maybe one of the regular washers along with a lock washer. I don't want to screw anything up though. So if this is a bad idea let me know!

When I install studs I chase the holes with a thread chaser and clean them out thoroughly with brake cleaner and air. I then chase the stud threads with nut type thread chaser. I burnish the threads on a fine wire wheel. At that point they should screw in and out very easily by hand. I set the studs based on height. I don't care if they are bottomed out as I use Red Loctite on them. After I install them I place a cylinder and head on the upper case and install washers and nuts. I lightly torque them up. This sets the stud up straight in the hole. I let it sit at least 24 hours before applying real torque to the nuts. I prefer to let the assembly sit for 48 hours.
Be careful using any type of thread locking compound on the 2 studs that provide oil to the top end. Apply the stuff with a toothpick to the hole threads. I know of one case where the compound rose up as the stud was being tightened and blocked the oil feed holes in the upper case.
Dipping in oil has its problems with the big one being the oil can drop to the bottom of the hole, hydro lock and give you a false tight.

brandEn · « **Reply #12 on:** April 30, 2011, 01:19:54 PM »

Thanks for the great post and advice Mike. I wish I had that tip the first time around. That should be in the tips and tricks section..... Mods?

MCRider · « **Reply #13 on:** April 30, 2011, 01:29:21 PM »

Repeating what has already been said and adding. I suspect the knock pin/locating dowels are holding the head up a skosh. Its a variable that has to be accounted for.

Then all the other stuff from Mike etc.

Good luck. Timely post as I'm putting my head on this weekend.

brandEn · « **Reply #14 on:** April 30, 2011, 01:35:19 PM »

I just measured my dowel locating pins and it seems I have enough room for them to not be an issue. I will shorten them a bit upon reinstallation just to eliminate this as a cause. I also double nutted up the studs again just to make sure they were all tight and they were. I am pretty sure my issue was due to a thin head gasket.

Also, the hydrolocking of the studs due to dipping in oil and having it run down the hole is definately something I would have never thought of in a million years. Great information and food for thought for sure.

MRieck · « **Reply #15 on:** April 30, 2011, 03:24:13 PM »

Quote from: MCRider on April 30, 2011, 01:29:21 PM

Repeating what has already been said and adding. I suspect the knock pin/locating dowels are holding the head up a skosh. Its a variable that has to be accounted for.

Then all the other stuff from Mike etc.

Good luck. Timely post as I'm putting my head on this weekend.

I agree.

brandEn · « **Reply #16 on:** May 03, 2011, 08:57:24 AM »

Anybody have a Cometic 836 gasket they could sell me? Apparently the machine that presses in the fire rings at the factory is broke. Or so I have been told. All gaskets on backorder till its fixed.

MRieck · « **Reply #17 on:** May 03, 2011, 10:05:45 AM »

Quote from: brandEn on May 03, 2011, 08:57:24 AM

Anybody have a Cometic 836 gasket they could sell me? Apparently the machine that presses in the fire rings at the factory is broke. Or so I have been told. All gaskets on backorder till its fixed.

I think I have one ...I'll check.

tweakin · « **Reply #18 on:** May 03, 2011, 12:05:35 PM »

Mike,

If you have one for Branden I can pay you for the 125-75 cam now and Branden and I can split shipping cost. It may be a bit longer than I first thought to gather the funds for the head work and I don't want to miss out on the cam. Damn kids daycare is cutting into my engine build fund, lol.

Quote from: MRieck on May 03, 2011, 10:05:45 AM

Quote from: brandEn on May 03, 2011, 08:57:24 AM
Anybody have a Cometic 836 gasket they could sell me? Apparently the machine that presses in the fire rings at the factory is broke. Or so I have been told. All gaskets on backorder till its fixed.
I think I have one ...I'll check.

brandEn · « **Reply #19 on:** May 03, 2011, 01:35:25 PM »

Quote from: MRieck on May 03, 2011, 10:05:45 AM

Quote from: brandEn on May 03, 2011, 08:57:24 AM
Anybody have a Cometic 836 gasket they could sell me? Apparently the machine that presses in the fire rings at the factory is broke. Or so I have been told. All gaskets on backorder till its fixed.
I think I have one ...I'll check.

If you have one I will take it. Thanks Mike.

twostick · « **Reply #20 on:** May 05, 2011, 12:30:55 PM »

Hello all. I am new here and other than owning and riding a 76 750k across Canada in 1984, no major experience with the engine to speak of. Hoping to acquire another one soon and rectify that. I have been around a lot of go-fast stuff in the meantime tho and have a couple of comments that may or may not help.

If you are using a Cometic gasket now and it is a metal multi-layer gasket like their automotive ones are, it is re-usable. If it isn't bent,burnt thru or gouged up just clean it 'till it looks like new and use it again.

My brother has an 1100 Goldwing that one head gasket kept leaking coolant from 3 times and it turned out to be loss of clamping force. He had the head re-surfaced and tried both replacement gaskets and Genuine Honda before he figured it out. Honda specifies a Moly paste (even had a Honda part# IIRC) when installing head gaskets. Specifically between the nut and the washer. Without it the friction uses up some of the torque and the gasket doesn't get the required clamping force and it fails shortly after. Guess what he hadn't been using. He did the job again, this time with the Moly and problem solved.

I would clean and chase ALL threads and install the fasteners to the MFG spec. ARP for instance has a different torque spec depending on whether you lube the threads with 10w30 or their own Moly assembly lube. Their stuff takes less torque. Hope this helps.

Kevin

MRieck · « **Reply #21 on:** May 05, 2011, 01:55:37 PM »

Quote from: twostick on May 05, 2011, 12:30:55 PM

Hello all. I am new here and other than owning and riding a 76 750k across Canada in 1984, no major experience with the engine to speak of. Hoping to acquire another one soon and rectify that. I have been around a lot of go-fast stuff in the meantime tho and have a couple of comments that may or may not help.

If you are using a Cometic gasket now and it is a metal multi-layer gasket like their automotive ones are, it is re-usable. If it isn't bent,burnt thru or gouged up just clean it 'till it looks like new and use it again.

My brother has an 1100 Goldwing that one head gasket kept leaking coolant from 3 times and it turned out to be loss of clamping force. He had the head re-surfaced and tried both replacement gaskets and Genuine Honda before he figured it out. Honda specifies a Moly paste (even had a Honda part# IIRC) when installing head gaskets. Specifically between the nut and the washer. Without it the friction uses up some of the torque and the gasket doesn't get the required clamping force and it fails shortly after. Guess what he hadn't been using. He did the job again, this time with the Moly and problem solved.

I would clean and chase ALL threads and install the fasteners to the MFG spec. ARP for instance has a different torque spec depending on whether you lube the threads with 10w30 or their own Moly assembly lube. Their stuff takes less torque. Hope this helps.

Kevin

I will have some of these next week. Everything up to this point has been copper or fiber composite.

MCRider · « **Reply #22 on:** May 05, 2011, 02:12:11 PM »

Mike:
Having never heard of a MLG, and reading up on it, I have this question. Can you add layers to make up for the amounts removed when planing a head or cylinder surface.

Or is that even necessary?
just wondering,
Ron

twostick · « **Reply #23 on:** May 05, 2011, 05:58:21 PM »

Quote from: MCRider on May 05, 2011, 02:12:11 PM

Mike:
Having never heard of a MLG, and reading up on it, I have this question. Can you add layers to make up for the amounts removed when planing a head or cylinder surface.

Or is that even necessary?
just wondering,
Ron

Cometic will build any thickness you want if you need to adjust deck height, compression ratio or piston to head clearance.

Kevin

brandEn · « **Reply #24 on:** May 05, 2011, 06:38:02 PM »

Quote from: MRieck on April 29, 2011, 07:36:29 PM

Did you lube the cylinder stud threads? Make sure the oil drain back dowels aren't to long not allowing the cylinder head to pull down enough. Also ...you asked me about CR carb manifolds for the F2. If memory serves correct you need the DOHC manifolds which probably accounts for the 220.00 figure you said for the right pieces. That is unless you find an old set of CR SOHC manifolds which where to big for the K (they did work with big cursing). They were long also.

Mike are you refering to the dowels between the case and cylinder or the dowels between the cylinder and head?

News:

Author Topic: 836 head gasket exhaust leak and loose head bolts after rebuild (Read 7509 times)