The 1 and 4 cylinders were both around 450psi, which is the upper end of the spec. On another forum someone is suggesting to close air into a cylinder and see where it is escaping. I am also thinking of pulling the head back off to see if it looks like the head isn't sealing (warped block.). I am not convinced that the engine is shot yet.
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I'd like to not condem it just yet either.The 1 and 4 cylinders were both around 450psi, which is the upper end of the spec. On another forum someone is suggesting to close air into a cylinder and see where it is escaping. I am also thinking of pulling the head back off to see if it looks like the head isn't sealing (warped block.). I am not convinced that the engine is shot yet.
The idea way to check if the rods were bent is to wind the engine over by hand and see where the pistons stop at the top of the block. If they all look like they are in the same position at TDC the rods should be ok.
Pushing air in with the valves closed is an idea, gives you an idea if something it not seating right lowering the compression. 450psi is good on the 2 good cylinders.
Hotrod1830
Well-known member
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- Sep 14, 2010
- Messages
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Applying compressed air to the cylinder is called a "leakdown" test. They make a tool for it, that tells you the percentage of leakage of a cylinder. The tool is best, but adapting the compression tester to accept a air hose will work. You just will not have any numbers to go by, just the sound.
Since you are down 300 psi on those cylinders, you shouldnt have a problem finding the leakage if there is some.
Your compression tester should have the short quick coupler. You can get air hose couplers to match it. Remove the valve from the compression tester hose(looks like a tire schrader valve)
GEt your cylinder up to TDC compression stroke and apply air pressure to it. Use the good cylinder as a baseline. Some leakage is normal. If you have leakage in the bad cylinder, it will sound alot different, and just follow the air. A bunch of air coming from the oil filler cap on a bad cylinder indicates ring leakage. Air coming from the adjacent cylinder means there is air leakage between cylinder. Air leakage from the radiator cap indicates it is going into the cooling system via a bad gasket or crack.
Since you are down 300 psi on those cylinders, you shouldnt have a problem finding the leakage if there is some.
Your compression tester should have the short quick coupler. You can get air hose couplers to match it. Remove the valve from the compression tester hose(looks like a tire schrader valve)
GEt your cylinder up to TDC compression stroke and apply air pressure to it. Use the good cylinder as a baseline. Some leakage is normal. If you have leakage in the bad cylinder, it will sound alot different, and just follow the air. A bunch of air coming from the oil filler cap on a bad cylinder indicates ring leakage. Air coming from the adjacent cylinder means there is air leakage between cylinder. Air leakage from the radiator cap indicates it is going into the cooling system via a bad gasket or crack.
I did the air test today. I didn't check in here first so just did my own version but it was pretty easy to figure it out. The air was coming right out the exhaust! Numbers 1 and 4 were super tight and the middle ones the air was rushing right out the exhaust. So it would appear that I received a bad head? I have it pulled right now. A buddy suggested spraying wd-40 into the exhaust ports and seeing if it leaked out the valves. One of them did for sure the other it wasn't noticeable as much. Those two were thick full of carbon sludge so I am thinking that mixed with the wd-40 may have "sealed" it enough to not see it dripping out. Looks like I will be calling the company i got the head from tomorrow and making a complaint!Applying compressed air to the cylinder is called a "leakdown" test. They make a tool for it, that tells you the percentage of leakage of a cylinder. The tool is best, but adapting the compression tester to accept a air hose will work. You just will not have any numbers to go by, just the sound.
Since you are down 300 psi on those cylinders, you shouldnt have a problem finding the leakage if there is some.
Your compression tester should have the short quick coupler. You can get air hose couplers to match it. Remove the valve from the compression tester hose(looks like a tire schrader valve)
GEt your cylinder up to TDC compression stroke and apply air pressure to it. Use the good cylinder as a baseline. Some leakage is normal. If you have leakage in the bad cylinder, it will sound alot different, and just follow the air. A bunch of air coming from the oil filler cap on a bad cylinder indicates ring leakage. Air coming from the adjacent cylinder means there is air leakage between cylinder. Air leakage from the radiator cap indicates it is going into the cooling system via a bad gasket or crack.
Glad the issue seems to be just the head, maybe they cut corners and didn't vacuum test it after doing the valves and seats.I did the air test today. I didn't check in here first so just did my own version but it was pretty easy to figure it out. The air was coming right out the exhaust! Numbers 1 and 4 were super tight and the middle ones the air was rushing right out the exhaust. So it would appear that I received a bad head? I have it pulled right now. A buddy suggested spraying wd-40 into the exhaust ports and seeing if it leaked out the valves. One of them did for sure the other it wasn't noticeable as much. Those two were thick full of carbon sludge so I am thinking that mixed with the wd-40 may have "sealed" it enough to not see it dripping out. Looks like I will be calling the company i got the head from tomorrow and making a complaint!
If it is their fault, i hope they give you a new head gasket too.
Figured I would give an update here. I finally got a new head sent to me under warranty. The first one was definitely bad. After spraying wd-40 in the exhaust ports you could see it leaking out the valves. I got the new one bolted on and figured I would do the air test before I got too far along. Well wouldn't you know numbers 2 and 3 still wouldn't hold air and you could feel it escaping from the push rod holes. So off the head came again! I then decided I would pour some mystery oil into each cylinder to see if it holds and 2 and 3 drained out in under an hour. So clearly the rings are shot. I believe I owe someone a 6 pack on that! Lol The cylinders really appear to be in good shape so I am leaning towards a rebuild rather than a replacement. Any tips or tricks on pulling the engine?Glad the issue seems to be just the head, maybe they cut corners and didn't vacuum test it after doing the valves and seats.
If it is their fault, i hope they give you a new head gasket too.
You can't catch a break can you?Figured I would give an update here. I finally got a new head sent to me under warranty. The first one was definitely bad. After spraying wd-40 in the exhaust ports you could see it leaking out the valves. I got the new one bolted on and figured I would do the air test before I got too far along. Well wouldn't you know numbers 2 and 3 still wouldn't hold air and you could feel it escaping from the push rod holes. So off the head came again! I then decided I would pour some mystery oil into each cylinder to see if it holds and 2 and 3 drained out in under an hour. So clearly the rings are shot. I believe I owe someone a 6 pack on that! Lol The cylinders really appear to be in good shape so I am leaning towards a rebuild rather than a replacement. Any tips or tricks on pulling the engine?
With the head off, do 2 & 3 rise to the same point on the block the other 2 do? If so, it could just need rings. Saves a re-co engine when you are already this far in.
Normally engine and pump come out as one. So, 8 or so hydro lines, and engine hoses/wires and the whole thing comes out.
No I certainly can't! Oh well just want to get it going now. Yes the pistons seem to do what they should and the cylinder walls are not even scored so I am hoping it will be an easy rebuild. Do I have to pull the pump with it? It appears that I can just get the belt off and remove only the engine but I haven't truly dug too deep yet. I am hoping to only remove what I need to.You can't catch a break can you?
With the head off, do 2 & 3 rise to the same point on the block the other 2 do? If so, it could just need rings. Saves a re-co engine when you are already this far in.
Normally engine and pump come out as one. So, 8 or so hydro lines, and engine hoses/wires and the whole thing comes out.
I believe you can pull the engine on it's own, it's just easier to remove the two as one. You will just have to get into it and see how the access is i guess.No I certainly can't! Oh well just want to get it going now. Yes the pistons seem to do what they should and the cylinder walls are not even scored so I am hoping it will be an easy rebuild. Do I have to pull the pump with it? It appears that I can just get the belt off and remove only the engine but I haven't truly dug too deep yet. I am hoping to only remove what I need to.
It looks like if I remove the flywheel the engine will unbolt from that shield that connects it to the hyrdropump. Looks like the block would slide right out from there but not sure if I am asking for trouble. I can't raise the cab as it's in my garage so getting at the hydropump lines will be difficult.I believe you can pull the engine on it's own, it's just easier to remove the two as one. You will just have to get into it and see how the access is i guess.
I have removed a different branded engine without pulling the pumps, so it can be done i believe, just harderIt looks like if I remove the flywheel the engine will unbolt from that shield that connects it to the hyrdropump. Looks like the block would slide right out from there but not sure if I am asking for trouble. I can't raise the cab as it's in my garage so getting at the hydropump lines will be difficult.
As it's in the shop that you can't lift the cab, you really have few choices.
Let me know how you go with pulling it and the repair!
Well I got the engine out and it is at the rebuilders. It really was pretty easy to get out separate from the pump. I guess we shall see if the install is just as smooth??I have removed a different branded engine without pulling the pumps, so it can be done i believe, just harder
As it's in the shop that you can't lift the cab, you really have few choices.
Let me know how you go with pulling it and the repair!
I'm sure it will be just as easy. With the head on, it may be a little harder as there is less space up the top, but you'll work that out.Well I got the engine out and it is at the rebuilders. It really was pretty easy to get out separate from the pump. I guess we shall see if the install is just as smooth??
Willl the rebuilders let you know what was wrong with the old one? i'd like to know what the issue was.
Hi Tazza. Sorry it has been so long but finally have some answers and a question. So they tore it down and the middle cylinders were shot. The rings were worn down pretty good. One of the valve seats also failed and was all over one of the cylinders. He also found some wear on the camshaft which was unrelated to the overheat. Long story short it wasn't worth trying to rebuild the engine. So I went with a reman one directly from Bobcat. It says it needs to have the oil pressure primed but I can't find anywhere in the book how to do that. Any tips?I'm sure it will be just as easy. With the head on, it may be a little harder as there is less space up the top, but you'll work that out.
Willl the rebuilders let you know what was wrong with the old one? i'd like to know what the issue was.
Hotrod1830
Well-known member
- Joined
- Sep 14, 2010
- Messages
- 513
You can pre lube them with a tool they make. It is basicly a air tank that you fill with oil and hook up to the oil pressure port on the engine. Apply air pressure to the tank and it forces oil into the engine via air pressure.Hi Tazza. Sorry it has been so long but finally have some answers and a question. So they tore it down and the middle cylinders were shot. The rings were worn down pretty good. One of the valve seats also failed and was all over one of the cylinders. He also found some wear on the camshaft which was unrelated to the overheat. Long story short it wasn't worth trying to rebuild the engine. So I went with a reman one directly from Bobcat. It says it needs to have the oil pressure primed but I can't find anywhere in the book how to do that. Any tips?
Most auto parts stores loan these tools out, as the reman engines they sell require them for warranty.
Engines can sit on shelves for moths or even years before being sold. The oil during assembly is long gone. Finding a way to pre lube it is cheap insurance.
Ok great. I will see if I can locate one of those tools. I realized that I forgot to move the oil pressure sensor over from the old engine. I tried to remove the plug from the new one and it is stripping on me. I will fight with that in the morning.You can pre lube them with a tool they make. It is basicly a air tank that you fill with oil and hook up to the oil pressure port on the engine. Apply air pressure to the tank and it forces oil into the engine via air pressure.
Most auto parts stores loan these tools out, as the reman engines they sell require them for warranty.
Engines can sit on shelves for moths or even years before being sold. The oil during assembly is long gone. Finding a way to pre lube it is cheap insurance.
Not great news, at least you know the reman engine will last.Ok great. I will see if I can locate one of those tools. I realized that I forgot to move the oil pressure sensor over from the old engine. I tried to remove the plug from the new one and it is stripping on me. I will fight with that in the morning.
The only other priming method is to spin the engine over with the fuel shut off solenoid disconnected so it won't start. The priming tool is a good idea for the lubrication system. When engines are build, they usually use grease on the cam lobes andcrank shaft bearings, so they should never start up dry.
I am back up and running! It is a sweet sound that I haven't heard in way too long. I am getting intermittent warning lights for low oil pressure. Is that likely just it getting fully lubricated? I guess I can get a gauge and check for sure. Just weird that it comes and goes.Not great news, at least you know the reman engine will last.
The only other priming method is to spin the engine over with the fuel shut off solenoid disconnected so it won't start. The priming tool is a good idea for the lubrication system. When engines are build, they usually use grease on the cam lobes andcrank shaft bearings, so they should never start up dry.
Is it an engine oil pressure warning or hydraulics?I am back up and running! It is a sweet sound that I haven't heard in way too long. I am getting intermittent warning lights for low oil pressure. Is that likely just it getting fully lubricated? I guess I can get a gauge and check for sure. Just weird that it comes and goes.
If the engine, throw a gauge on it, see what the actual reading is. The sender bay be bad and reading low. There is no reason for the engine pressure to be changing, after it primes, it's done, it should not change. It will lower slightly when warm as the oil thins out, but it should be pretty constant.
I would guess a bad sensor. But like you said a gauge will verify itIs it an engine oil pressure warning or hydraulics?
If the engine, throw a gauge on it, see what the actual reading is. The sender bay be bad and reading low. There is no reason for the engine pressure to be changing, after it primes, it's done, it should not change. It will lower slightly when warm as the oil thins out, but it should be pretty constant.
