656 Gas Hydro Blown Head Gasket and Holy Valve

[tstoub77]

Hi, I recently joined this forum because it became apparent to me quickly that you were the gurus I seek. I'm new, I'm not afraid, but I do have a budget.

656 Gas Hydro has had a misfire and I finally was able to get into it for what I had hoped would just be a valve adjustment. #3 had a lot of oil around the manifold and showed fouled plugs. The valves were in desperate need of adjusting, but still I lost compression in #4 out through the manifold after setting the proper lash. I pulled the head.

The Head gasket was blown between 3 & 4 and had wear showing between 2 & 3. There's a hole in a valve in #4 as well and there is a lot of built up deposits. I plan to replace the entire valve train and bring the head into a machine shop to true it. I'd like to avoid anything more than cleaning up the deposits from bottom end if possible.

After some reading, I've come to understand that what I'm seeing is possible after overheating and I did that once a year prior after unknowingly losing my fan belt while plowing. Since this machine doesn't see too much heavy work, I didn't really notice a performance issue until late 2023.

What are your thoughts? I'm curious as to your suspicion for the cause of this issue and if you think I can avoid pulling the block apart and rebuilding it completely. What are some key metrics to make that call accurately? TIA

 

[rustred]

your correct on sending the head out for rebuild. it needs a shaving. i do see some valves that look recessed. and that burnt one that looks like it had a bite taken out of it. i would be pulling the pistons and inspecting the skirts for scoring for sure along with the rest. then you need to check the block for flatness also. the more u take apart the more you will find. darn near looks like it had starting fluid sprayed in there for more power ? no sense me giving info on the head as a good shop knows all that stuff. so i would pull pistons and "show me"lol.

 

[Janicholson]

I would clean and look at the cylinder walls very carefully for score marks up and down. Moving the pistons as needed to clean and inspect. If there is a ridge that you can feel with your fingernail. at the top of any cylinder (where the top piston ring stops, it needs a kit (sold here). The head surfacing would be needed if the blown gasket has etched into the head casting or block. I would specify Perfect circle style valve guide seals when the head is rebuilt. Flatness across the block and head should be no more than .001" per foot of surface. Jim

 

[Dieseltech]

I'll bet the engine needs sleeves/pistons/rings too. Years ago I pulled the head on a gas 560 for a neighbor with two burned exhaust valves do to oil burning that owner said is "not that bad". Got the head fixed, put it back on and did the SAME THING ten hours later as owner didn't want to replace the sleeves/pistons/rings and do it right the first time. Excess oil past rings will burn exhaust valves/seats if rings are bad enough.

 

[tstoub77]

I would clean and look at the cylinder walls very carefully for score marks up and down. Moving the pistons as needed to clean and inspect. If there is a ridge that you can feel with your fingernail. at the top of any cylinder (where the top piston ring stops, it needs a kit (sold here). The head surfacing would be needed if the blown gasket has etched into the head casting or block. I would specify Perfect circle style valve guide seals when the head is rebuilt. Flatness across the block and head should be no more than .001" per foot of surface. Jim

Being new to this endeavor, how does one check the block in frame and in the shed? I can figure out how to pull the sleeves, but checking the true-ness of this block and pressing in the new sleeves is where I am racking my brain a little right now.

 

[tstoub77]

I'll bet the engine needs sleeves/pistons/rings too. Years ago I pulled the head on a gas 560 for a neighbor with two burned exhaust valves do to oil burning that owner said is "not that bad". Got the head fixed, put it back on and did the SAME THING ten hours later as owner didn't want to replace the sleeves/pistons/rings and do it right the first time. Excess oil past rings will burn exhaust valves/seats if rings are bad enough.

It’s looking like an in-frame rebuild is in my near future. Tear down is no problem for me, but how I’ll be confirming block integrity and installing sleeves require more insight if you have any helpful guidance to share.

 

[used red MN]

Hi, I recently joined this forum because it became apparent to me quickly that you were the gurus I seek. I'm new, I'm not afraid, but I do have a budget.

656 Gas Hydro has had a misfire and I finally was able to get into it for what I had hoped would just be a valve adjustment. #3 had a lot of oil around the manifold and showed fouled plugs. The valves were in desperate need of adjusting, but still I lost compression in #4 out through the manifold after setting the proper lash. I pulled the head.

The Head gasket was blown between 3 & 4 and had wear showing between 2 & 3. There's a hole in a valve in #4 as well and there is a lot of built up deposits. I plan to replace the entire valve train and bring the head into a machine shop to true it. I'd like to avoid anything more than cleaning up the deposits from bottom end if possible.

After some reading, I've come to understand that what I'm seeing is possible after overheating and I did that once a year prior after unknowingly losing my fan belt while plowing. Since this machine doesn't see too much heavy work, I didn't really notice a performance issue until late 2023.

What are your thoughts? I'm curious as to your suspicion for the cause of this issue and if you think I can avoid pulling the block apart and rebuilding it completely. What are some key metrics to make that call accurately? TIAView attachment 2343View attachment 2344View attachment 2345View attachment 2346

Hello ts welcome to YT! See how the top number 4 piston and the area around the valves in the head is clean as a whistle? Okay, to others here yes it has not been firing due to the chunk missing out of the valve but the rings are pumping a lot of oil past the piston in that cylinder. Run that piston down to the bottom of the stroke, my bet is it will be obvious what you need to do. I am guessing the cylinder walls are badly scored in that hole. Meaning there are heavy scratches up and down. Now also to others I know this is not a spec but I just went over to my tool box an did this to give him an approximation of what a ring ledge that is to severe would feel like. Ts get a. 0.008” feeler gauge hold it against something flat with one hand. The take your other thumb or finger and get a feel for the step up you feel. Compare that offset or step to what you feel at the ridge the rings have wore into the cylinders. If you feel the two are nearly comparable, the sleeves are wore to the point where just replacing the rings would not be a reliable repair. And by the way your valve is “holey” not holy, your the one that needs to pray, it is to late for the valve!

 

[Janicholson]

Being new to this endeavor, how does one check the block in frame and in the shed? I can figure out how to pull the sleeves, but checking the true-ness of this block and pressing in the new sleeves is where I am racking my brain a little right now.

one example A quality straight edge is needed. It should be a 3 footer if possible. Measuring under the bar when it is placed on edge on a clean head or block using a thin feeler gauge along its length to measure any warp. U tube will have videos. Jim

 

[Fritz Maurer]

Anyone heard from tractor vet? He could tell this guy how to fix it, how to build a Y-block Ford, and how to haul coal with a twin stick Mack… all in the same breath!

 

[rustred]

It’s looking like an in-frame rebuild is in my near future. Tear down is no problem for me, but how I’ll be confirming block integrity and installing sleeves require more insight if you have any helpful guidance to share.

once you get it torn down then a person can give proper info without guessing. we dont know what u have for tools. nor your engine experience .

 

[rustred]

Anyone heard from tractor vet? He could tell this guy how to fix it, how to build a Y-block Ford, and how to haul coal with a twin stick Mack… all in the same breath!

not for a while.

 

[rustred]

Hello ts welcome to YT! See how the top number 4 piston and the area around the valves in the head is clean as a whistle? Okay, to others here yes it has not been firing due to the chunk missing out of the valve but the rings are pumping a lot of oil past the piston in that cylinder. Run that piston down to the bottom of the stroke, my bet is it will be obvious what you need to do. I am guessing the cylinder walls are badly scored in that hole. Meaning there are heavy scratches up and down. Now also to others I know this is not a spec but I just went over to my tool box an did this to give him an approximation of what a ring ledge that is to severe would feel like. Ts get a. 0.008” feeler gauge hold it against something flat with one hand. The take your other thumb or finger and get a feel for the step up you feel. Compare that offset or step to what you feel at the ridge the rings have wore into the cylinders. If you feel the two are nearly comparable, the sleeves are wore to the point where just replacing the rings would not be a reliable repair. And by the way your valve is “holey” not holy, your the one that needs to pray, it is to late for the valve!

he said this engine was overheated, so that is the out come., engine overhaul. and yes they will pump oil. and yes if you catch you finger nail on the ring ledge its worn enough for replacing. it is kinda foolish only redoing the head on a heated and worn engine. best is to concentrate on getting the pistons out then analyze it farther. also would be nice to have a look at the spark plugs, but i can picture them.

 

[used red MN]

Anyone heard from tractor vet? He could tell this guy how to fix it, how to build a Y-block Ford, and how to haul coal with a twin stick Mack… all in the same breath!

Na, I think even he would need to take two breaths for that. I was thinking about making a post asking about him. I think some on here correspond with him in other ways. Kind of wondered if the forum change over flipped his switch.

 

[tstoub77]

Hello ts welcome to YT! See how the top number 4 piston and the area around the valves in the head is clean as a whistle? Okay, to others here yes it has not been firing due to the chunk missing out of the valve but the rings are pumping a lot of oil past the piston in that cylinder. Run that piston down to the bottom of the stroke, my bet is it will be obvious what you need to do. I am guessing the cylinder walls are badly scored in that hole. Meaning there are heavy scratches up and down. Now also to others I know this is not a spec but I just went over to my tool box an did this to give him an approximation of what a ring ledge that is to severe would feel like. Ts get a. 0.008” feeler gauge hold it against something flat with one hand. The take your other thumb or finger and get a feel for the step up you feel. Compare that offset or step to what you feel at the ridge the rings have wore into the cylinders. If you feel the two are nearly comparable, the sleeves are wore to the point where just replacing the rings would not be a reliable repair. And by the way your valve is “holey” not holy, your the one that needs to pray, it is to late for the valve!

Great feedback, thank you! I used Holy in reference to what followed it when I saw the valve! lol

 

[tstoub77]

once you get it torn down then a person can give proper info without guessing. we dont know what u have for tools. nor your engine experience .

I can access most tools and I have someone that can help if I really get myself into trouble. Engine experience is somewhat extensive on two stroke toys and motorcycle repair but I left most of that in my youth 25 years ago. Now I’m playing farmer and ridiculously ready to dive into yet another project before spring planting weather arrives. All of this in my free time after the full time work and in between helping mama with the 6 kiddos

 

[BarnyardEngineering]

Anyone heard from tractor vet? He could tell this guy how to fix it, how to build a Y-block Ford, and how to haul coal with a twin stick Mack… all in the same breath!

If he did respond, I'm pretty sure the first thing, and maybe the only thing, he would say is, that is why you run LOW ASH oil. That torch hole in the valve is exactly what the IH low ash oil prevented.

 

[caterpillar guy]

All good advice here from all. Now for the sleeves after you clean the block up so you could eat off from it. You need to check the counter bores for depth and if there are any shims left in them. Once they are all cleaned up then with a mic and depth gauge you can compare the lip thickness on the sides of the sleeves versus the depth of the counter bore this will give you an idea of how much if any shim you need for the sleeve protrusion. They need to be very close to the same height and only about 2or3 thousandths up with less than .001 to .0015 difference for your head gasket to work well. then torque according to your book specs and make sure you retorque it after you run it to temperature. As long as it is warm to the touch it will be warm enough then reset your valve lash after the retorque. Use the best head gasket you can find. Those cheap tin gaskets with no sandwich to them are junk. You will also need the check ring end gap with them in the sleeve in the block setting all these according to the cylinder you checked them in not to mix them up. Same thing for the pistons with the side clearance and roundness of the holes. Both before and after the sleeves are in. With the crank in and the new mains in check the oil clearance with some plastigage.
It is also made for the clearance you need. So if you want a clearance of .001-.002 then that is the one you want to get . Not the .003-.005 . After you have the mains done then check the rods by the same method.

 

[tstoub77]

All good advice here from all. Now for the sleeves after you clean the block up so you could eat off from it. You need to check the counter bores for depth and if there are any shims left in them. Once they are all cleaned up then with a mic and depth gauge you can compare the lip thickness on the sides of the sleeves versus the depth of the counter bore this will give you an idea of how much if any shim you need for the sleeve protrusion. They need to be very close to the same height and only about 2or3 thousandths up with less than .001 to .0015 difference for your head gasket to work well. then torque according to your book specs and make sure you retorque it after you run it to temperature. As long as it is warm to the touch it will be warm enough then reset your valve lash after the retorque. Use the best head gasket you can find. Those cheap tin gaskets with no sandwich to them are junk. You will also need the check ring end gap with them in the sleeve in the block setting all these according to the cylinder you checked them in not to mix them up. Same thing for the pistons with the side clearance and roundness of the holes. Both before and after the sleeves are in. With the crank in and the new mains in check the oil clearance with some plastigage.
It is also made for the clearance you need. So if you want a clearance of .001-.002 then that is the one you want to get . Not the .003-.005 . After you have the mains done then check the rods by the same method.

I went for the total rebuild. Had a guy check the block and short block the bottom end and machined the head back to flat. Now for the trouble…. I assembled it all, went to fire it up, and the head gasket leaked coolant all the way around! So now I’m back where I started. Any tips for this head gasket? I think I’ll go again with copper coat this time and run it before adding coolant to get the retorque opportunity. Any other suggestions are appreciated.

 

[used red MN]

Did you follow what Caterpillar Guy posted above about the sleeve protrusion? Maybe you thought he was just pumping wind? Well if you didn’t it is “getting your goat” now! Did you run a tap in all the thread bolt holes and blow them out clean. Did you buff the head bolt threads with a power brush or wire brush wheel on a bench grinder then check any that looked questionable by making sure they screw all the way in the block? Did you oil the bolt threads and the contact surface under the bolt head that tightened against the head? Did you torque the head in sequence in at least 3 steps adjusting the torque higher each time, like 50, then 80 then final whatever that setting is? Did you go through the torque sequence a second time on your final torque? Usually many of the first tighten bolts will turn down more. When you get it apart show us a picture of the head gasket both on the head and on the block. Why do you think you want to run it without water next time to warm it up? The gasket when right as in everything done mentioned here and by Cat guy does not leak coolant after install. If it does there is a problem that needs investigated.

 

[Fritz Maurer]

I went for the total rebuild. Had a guy check the block and short block the bottom end and machined the head back to flat. Now for the trouble…. I assembled it all, went to fire it up, and the head gasket leaked coolant all the way around! So now I’m back where I started. Any tips for this head gasket? I think I’ll go again with copper coat this time and run it before adding coolant to get the retorque opportunity. Any other suggestions are appreciated.

Well… that’s one sure way to crack the head…