Shed Head repair
Discussion
I have a Mitsubishi Express 4wd van that's mainly used for towing duties, with 350,000 km under it's belt.
It had a head gasket failure, and the gasses have eroded the head on their way to the water jacket. The fire ring section of the head is ok - the erosion starts about 4 mm from the combustion chamber.
To get the head repaired is not cheap (strip completely, heat, weld, resurface, reassemble, seat valves etc).
I am chasing a second-hand head or engine, but haven't found one yet.
So I was contemplating filling the eroded area with metal filled epoxy, probably JB Weld. The aim is to keep it running for another year or so.
I am aware of the issues bonding to alumimium, and would clean and roughen the surface, then wet-sand through a layer of epoxy to remove the surface oxide.
Does this approach have any chance of succeeding? I know it's a bodge, but fishing season is on us here (AUS), and I can't afford a new tow vehicle.
It had a head gasket failure, and the gasses have eroded the head on their way to the water jacket. The fire ring section of the head is ok - the erosion starts about 4 mm from the combustion chamber.
To get the head repaired is not cheap (strip completely, heat, weld, resurface, reassemble, seat valves etc).
I am chasing a second-hand head or engine, but haven't found one yet.
So I was contemplating filling the eroded area with metal filled epoxy, probably JB Weld. The aim is to keep it running for another year or so.
I am aware of the issues bonding to alumimium, and would clean and roughen the surface, then wet-sand through a layer of epoxy to remove the surface oxide.
Does this approach have any chance of succeeding? I know it's a bodge, but fishing season is on us here (AUS), and I can't afford a new tow vehicle.
Might work better than you think. This guy managed to make an entire head (albeit a simple one) out of JB Weld. Apparently it can withstand temperatures up to around 260c, I don't know what kind of temperature the head typically reaches but coolant temp is normally no more than around 95c so I'm crossing fingers for you
https://youtu.be/587RuL45jS8
https://youtu.be/587RuL45jS8
E-bmw said:
On something like an engine you describe on a high duty like you say no, it won't.
The engine in the video is significantly lower duty & stress & let's face it a head made of hard wood would do what that one did.
Interestingly the guy who made the video tried a plywood head in another experiment and it did work pretty well for a short timeThe engine in the video is significantly lower duty & stress & let's face it a head made of hard wood would do what that one did.
No pics at the moment. It is / was fine for light running, but at WOT it slowly pressurises the cooling system until it "burps" about 1/2 cup of coolant out the radiator overflow.
I took the head off at a mate's place - he just wodged some epoxy putty in so we could put it back together and I could drive it home. However it was a bit of a rushed job, and it started to pressurise the rad again after about a week.
As far as temperature, JB is good to 260 C. There are better aluminium epoxies, but only rated to 120 C.
I'll keep searching for a second hand head / engine while I ponder the epoxy idea.
I took the head off at a mate's place - he just wodged some epoxy putty in so we could put it back together and I could drive it home. However it was a bit of a rushed job, and it started to pressurise the rad again after about a week.
As far as temperature, JB is good to 260 C. There are better aluminium epoxies, but only rated to 120 C.
I'll keep searching for a second hand head / engine while I ponder the epoxy idea.
227bhp said:
It's difficult to say without seeing it, but temperature aside it also needs to be able to really key to the metal too. Running an aluminium burr down it to rough it up and clean it and also drill some holes in will see a good bond - it's just like filling teeth.
Hence my comment about wet sanding.Bonding to Alumimium is a tricky business, as you need to remove the surface oxide layer to get to the alloy.
I expected the original putty patchup to fail, as we didn't have time to do do it properly, and used a quick-set putty just to get it home.
AW111 said:
227bhp said:
It's difficult to say without seeing it, but temperature aside it also needs to be able to really key to the metal too. Running an aluminium burr down it to rough it up and clean it and also drill some holes in will see a good bond - it's just like filling teeth.
Hence my comment about wet sanding.Bonding to Alumimium is a tricky business, as you need to remove the surface oxide layer to get to the alloy.
I expected the original putty patchup to fail, as we didn't have time to do do it properly, and used a quick-set putty just to get it home.
I would recommend getting the head properly skimmed afterwards though.
AW111 said:
No pics at the moment. It is / was fine for light running, but at WOT it slowly pressurises the cooling system until it "burps" about 1/2 cup of coolant out the radiator overflow.
I took the head off at a mate's place - he just wodged some epoxy putty in so we could put it back together and I could drive it home. However it was a bit of a rushed job, and it started to pressurise the rad again after about a week.
As far as temperature, JB is good to 260 C. There are better aluminium epoxies, but only rated to 120 C.
I'll keep searching for a second hand head / engine while I ponder the epoxy idea.
Have you checked for combustion gasses in the cooling system? Fine on light running but pressurising on WOT could be a radiator or water pump problem. You might be looking in the wrong place. I took the head off at a mate's place - he just wodged some epoxy putty in so we could put it back together and I could drive it home. However it was a bit of a rushed job, and it started to pressurise the rad again after about a week.
As far as temperature, JB is good to 260 C. There are better aluminium epoxies, but only rated to 120 C.
I'll keep searching for a second hand head / engine while I ponder the epoxy idea.
Little Pete said:
Have you checked for combustion gasses in the cooling system? Fine on light running but pressurising on WOT could be a radiator or water pump problem. You might be looking in the wrong place.
Radiator replaced first, as the core was leaking due to the raised pressure. Water pump replaced about 5 years ago.The head is definitely damaged, as shown by the erosion into the water gallery.
AW111 said:
Radiator replaced first, as the core was leaking due to the raised pressure. Water pump replaced about 5 years ago.
The head is definitely damaged, as shown by the erosion into the water gallery.
Ok. I've seen a repair on a head on the outside using an epoxy and that was fine up to normal operating temp and pressure. I've never seen it used on the inside but I can't think of a reason why it wouldn't work. The head is definitely damaged, as shown by the erosion into the water gallery.
Update :
I ended up stripping the head of all bar valve guides and seats, and had it welded. I found the head repair bloke via a friend's workshop, so got it done as trade with the understanding that he would weld and deck the head only, not refurbish it.
The exhaust valves were a bit pitted, so I had him reseat them too.
It ended up costing me $150 for the work, and the same again for gaskets and coolant.
I will be using it to trailer a rally car 250 km to an event in a couple of weeks, with 30+ degrees C forecast, so decided to do the job properly.
I ended up stripping the head of all bar valve guides and seats, and had it welded. I found the head repair bloke via a friend's workshop, so got it done as trade with the understanding that he would weld and deck the head only, not refurbish it.
The exhaust valves were a bit pitted, so I had him reseat them too.
It ended up costing me $150 for the work, and the same again for gaskets and coolant.
I will be using it to trailer a rally car 250 km to an event in a couple of weeks, with 30+ degrees C forecast, so decided to do the job properly.
E-bmw said:
Is the right answer, keep us informed.
I'm currently caning it to work & back : full throttle up every hill with the aircon on in 30+ temps - no sign of trouble yet, but I've only done about 100 km so far. Being a naturally aspirated petrol with only 2.3 litres capacity, it works hard when towing : last time I did the trip it was back to 3rd for every hill, and 2nd for one steep pinch.
Gassing Station | Engines & Drivetrain | Top of Page | What's New | My Stuff