GearHead36
Well-Known Member
A few years ago, I bought a used Cub Cadet Pro Z 154S with a Kohler Confidant EZT750-3011 (747cc, 27HP, EFI) engine. I got it for a good price because it needed repairs. I did the repairs needed to get it into service, and used it for about a half season. It seemed to run well and cut well except in dense grass, where it struggled. Which surprised me a bit. I thought that 27HP on a 54" deck should power through even the thick stuff like a hot knife through butter.
During the next off-season, I decided to tackle some items I didn't do during the initial repair phase when I just wanted to get it into service as quickly as possible. I pulled the engine, and cleaned everything up so I could inspect for problems. I discovered that most of the cooling fins were completely clogged with what looked like a mixture of oil and dust. The valve covers appeared to be leaking so I suspected that the oil from the valve covers was mixing with the dust that was being sucked through the fins. So I cleaned out the fins, adjusted the valves again since it likely overheated in that half season of use, and sealed up the valve covers with gasket maker. I use Permatex 25228 The Right Stuff 90 Minute Black Gasket Maker, recommended by Taryl.
It ran fine for almost two seasons. No struggling in dense grass. Then it died. After checking some things. I'm pretty sure the head gaskets are blown. After it ran that long, I thought I'd dodged the bullet from those clogged fins. Apparently not. The gasket maker worked, though. No more leaking valve covers, but it still has an oil leak. Possibly due to the blown head gaskets, but at this point, I don't know. So I ordered this gasket kit:
which contains both head gaskets (with an updated design) and a bunch of seals and other gaskets. I plan to replace as much as I can without removing the crankshaft and pistons. That should allow me to replace the head gaskets, valve stem seals, main oil seal, and intake & exhaust manifold gaskets. I also plan to lap the valves, redo the RTV on the oil pan (using gasket maker), and adjust the valves again. Given that this engine likely overheated, is there anything else I should do while I have it apart? This engine is heavy, and the way it sits down between the fuel tanks, I have to rig up a lifting system to get it out. It's a bit of a pain to pull the engine, so I'd like to never have to do that again. This is my 3rd riding mower. I never had to pull engines on the previous two, so this should be an achievable goal, especially for a commercial engine in a residential application. It's only getting 40-50 hrs per yr of use. I would LIKE to, once a year, just have to do normal maintenance stuff. So far, every year, I've had to pull the engine. I admit, one year was due to a mistake on my part... maybe. I found a loose oil filter (my mistake) which I thought caused the oil leak I found, but now I'm thinking that the head gaskets may have been marginal the whole time I've owned it. And maybe the blowby from a marginal head gasket caused the leak. I'm still leaning toward the loose oil filter being the main problem. Two seasons ago, near the end of the season (when the oil filter would have been loosest), I had to add oil every time I used it. Last season, I think I added oil once.
I think most of my problems have been caused by oil leaks, which have resulted in clogged fins. Getting adequate access to the fins to clean them all requires pulling the engine. I want to eliminate all oil leaks in this repair. I don't mow in wet conditions. so hopefully, with nothing but dry dust rushing past the fins, they will stay clean for years.
I'm not sure I've ever had this engine run at it's full potential. I'm anxious to see how this thing runs once I get everything fixed.
Re: blown head gaskets.... I watched a few head gasket replacement videos, and some of the mowers & engines looked well cared for. Do head gaskets just blow on well maintained engines? I wouldn't think so, but one or two of those videos made me doubt that.
Here's a video of Taryl doing head gaskets on a JD mower that looks in good shape:
The mower and engine look like new. The deck looks good, but not like new. The front tires look about worn out, so it looks like it may have a lot of hours, but it looks well maintained. I wouldn't expect a blown head gasket on such a machine.
During the next off-season, I decided to tackle some items I didn't do during the initial repair phase when I just wanted to get it into service as quickly as possible. I pulled the engine, and cleaned everything up so I could inspect for problems. I discovered that most of the cooling fins were completely clogged with what looked like a mixture of oil and dust. The valve covers appeared to be leaking so I suspected that the oil from the valve covers was mixing with the dust that was being sucked through the fins. So I cleaned out the fins, adjusted the valves again since it likely overheated in that half season of use, and sealed up the valve covers with gasket maker. I use Permatex 25228 The Right Stuff 90 Minute Black Gasket Maker, recommended by Taryl.
It ran fine for almost two seasons. No struggling in dense grass. Then it died. After checking some things. I'm pretty sure the head gaskets are blown. After it ran that long, I thought I'd dodged the bullet from those clogged fins. Apparently not. The gasket maker worked, though. No more leaking valve covers, but it still has an oil leak. Possibly due to the blown head gaskets, but at this point, I don't know. So I ordered this gasket kit:
Amazon.com : Kohler 32-755-09-S Lawn & Garden Equipment Engine Gasket Set Genuine Original Equipment Manufacturer (OEM) Part : Lawn Mower Deck Parts : Patio, Lawn & Garden
Amazon.com : Kohler 32-755-09-S Lawn & Garden Equipment Engine Gasket Set Genuine Original Equipment Manufacturer (OEM) Part : Lawn Mower Deck Parts : Patio, Lawn & Garden
www.amazon.com
which contains both head gaskets (with an updated design) and a bunch of seals and other gaskets. I plan to replace as much as I can without removing the crankshaft and pistons. That should allow me to replace the head gaskets, valve stem seals, main oil seal, and intake & exhaust manifold gaskets. I also plan to lap the valves, redo the RTV on the oil pan (using gasket maker), and adjust the valves again. Given that this engine likely overheated, is there anything else I should do while I have it apart? This engine is heavy, and the way it sits down between the fuel tanks, I have to rig up a lifting system to get it out. It's a bit of a pain to pull the engine, so I'd like to never have to do that again. This is my 3rd riding mower. I never had to pull engines on the previous two, so this should be an achievable goal, especially for a commercial engine in a residential application. It's only getting 40-50 hrs per yr of use. I would LIKE to, once a year, just have to do normal maintenance stuff. So far, every year, I've had to pull the engine. I admit, one year was due to a mistake on my part... maybe. I found a loose oil filter (my mistake) which I thought caused the oil leak I found, but now I'm thinking that the head gaskets may have been marginal the whole time I've owned it. And maybe the blowby from a marginal head gasket caused the leak. I'm still leaning toward the loose oil filter being the main problem. Two seasons ago, near the end of the season (when the oil filter would have been loosest), I had to add oil every time I used it. Last season, I think I added oil once.
I think most of my problems have been caused by oil leaks, which have resulted in clogged fins. Getting adequate access to the fins to clean them all requires pulling the engine. I want to eliminate all oil leaks in this repair. I don't mow in wet conditions. so hopefully, with nothing but dry dust rushing past the fins, they will stay clean for years.
I'm not sure I've ever had this engine run at it's full potential. I'm anxious to see how this thing runs once I get everything fixed.
Re: blown head gaskets.... I watched a few head gasket replacement videos, and some of the mowers & engines looked well cared for. Do head gaskets just blow on well maintained engines? I wouldn't think so, but one or two of those videos made me doubt that.
Here's a video of Taryl doing head gaskets on a JD mower that looks in good shape:
The mower and engine look like new. The deck looks good, but not like new. The front tires look about worn out, so it looks like it may have a lot of hours, but it looks well maintained. I wouldn't expect a blown head gasket on such a machine.
