Bobcat 632 - Blown Head Gasket?

[bobcatzack]

As mentioned in prior posts, I have a 1978 Bobcat 632 that I bought a couple of months ago. It starts and runs now but is consuming coolant by the gallons .. with white cloud-like fumes coming off from the exhaust pipe .. then within about 5 minutes running at idle, the coolant level drops (since it evaporates so quickly) and the engine starts heating up!
Being a rookie, I am not sure what is going on but from reading various websites and forums I gather that the head gasket might be blown .. and as such the coolant leaks into the combustion chamber to burn off and evaporate (fast!).

I have no idea how I would be able to do this alone, but contemplating pulling the engine and see if I can get to the head gasket .. and possibly replace it. From experienced folks in this forum, can I get some suggestions for the following:

(1) can the engine be pulled without the hoist that everyone seem to use? I don't have such a hoist and am thinking of creating a wooden platform behind the Bobcat to possibly slide the engine out .. is that even practical?

(2) If I indeed was able to pull the engine out, should I look into actually rebuilding it? If so, is that a very difficult and challenging task? Very expensive?

(3) Any other related advise from experts would be highly appreciated!

MANY THANKS!

Quick Background:
(A) Replaced radiator / radiator hoses (B) Added new electronic ignition distributor / flame thrower (C) New spark plugs (D) New starter (E) New carburetor (F) Compression tests at 110-90-110-110 (G) Engine is always oily from outside with tons of sludge at the bottom (H) Hydraulics seem to be fine - bucket is able to lift and maneuver 900 pound round bales for my horses (I) I realize that I made a bad decision buying this Bobcat, but at this point I feel if I put enough effort (and money!) to get it running correctly, it might be a useful addition to my homestead (I) So far I have about 6K into it.

 

[bobcatzack]

As mentioned in prior posts, I have a 1978 Bobcat 632 that I bought a couple of months ago. It starts and runs now but is consuming coolant by the gallons .. with white cloud-like fumes coming off from the exhaust pipe .. then within about 5 minutes running at idle, the coolant level drops (since it evaporates so quickly) and the engine starts heating up!
Being a rookie, I am not sure what is going on but from reading various websites and forums I gather that the head gasket might be blown .. and as such the coolant leaks into the combustion chamber to burn off and evaporate (fast!).

I have no idea how I would be able to do this alone, but contemplating pulling the engine and see if I can get to the head gasket .. and possibly replace it. From experienced folks in this forum, can I get some suggestions for the following:

(1) can the engine be pulled without the hoist that everyone seem to use? I don't have such a hoist and am thinking of creating a wooden platform behind the Bobcat to possibly slide the engine out .. is that even practical?

(2) If I indeed was able to pull the engine out, should I look into actually rebuilding it? If so, is that a very difficult and challenging task? Very expensive?

(3) Any other related advise from experts would be highly appreciated!

MANY THANKS!

Quick Background:
(A) Replaced radiator / radiator hoses (B) Added new electronic ignition distributor / flame thrower (C) New spark plugs (D) New starter (E) New carburetor (F) Compression tests at 110-90-110-110 (G) Engine is always oily from outside with tons of sludge at the bottom (H) Hydraulics seem to be fine - bucket is able to lift and maneuver 900 pound round bales for my horses (I) I realize that I made a bad decision buying this Bobcat, but at this point I feel if I put enough effort (and money!) to get it running correctly, it might be a useful addition to my homestead (I) So far I have about 6K into it.

video from tonight on how the engine runs at idle - I have the radiator cap off - if I put the cap on and tighten it, immediately dense white smoke comes out the exhaust pipe and soon engine starts heating up. Strange that the engine does not heat up and no fumes are produced if the cap is off! Perhaps less pressure inside to push the coolant into the combustion chamber? Also noticeable in the video is exhaust fumes coming out of the engine oil cap opening - is this oil blowby or exhaust I cannot tell.

 

[plrngr2200]

I'm pretty new to Bobcats specifically, but based on the amount of pressure coming out of the cooling system and the amount of antifreeze its consuming I would say its a head gasket. If you can get the engine out of the machine it's definitely worth putting a new gasket in. One thing you should check is if the block or the head warped at all at the mating surface. This can happen if the engine overheats, which usually goes hand in hand with a blown head gasket. If it is warped you should be able to send it to a machine shop and have the surface milled down.

 

[bobcatzack]

I'm pretty new to Bobcats specifically, but based on the amount of pressure coming out of the cooling system and the amount of antifreeze its consuming I would say its a head gasket. If you can get the engine out of the machine it's definitely worth putting a new gasket in. One thing you should check is if the block or the head warped at all at the mating surface. This can happen if the engine overheats, which usually goes hand in hand with a blown head gasket. If it is warped you should be able to send it to a machine shop and have the surface milled down.

Thank you! I will make sure to check if the head is warped .. once I get to it!

 

[oiu789]

Also check for a cracked head or block.

 

[Hotrod1830]

The smoke you are seeing from the crankcase breather is either blowby or steam from the coolant leak. More than likely it is steam based on the fact I dont see a big lingering cloud. It looks like steam.
The cylinder head gasket can be done in chassis if need be, but it is a good idea to pull the engine and at least check the rod and crank bearings. coolant in the oil will kill bearings in a hurry. If it has good oil pressure and there is no metal shavings in the oil/filter you are probably OK. Unless you are planning on a overhaul anyway. You should be able to tell if the gasket is blown visually. As stated, it could be a cracked head as well, so take the head to a machine shop and have it checked for cracks regrdless if you see a gasket failure BEFORE any work is done. Overheating can crack heads. If no cracks; clean, surface, valve job and valve seals are recommended. Check cylinders for wear and scoring.
Engine hoists can be rented from a local rental yard in most area's. Call around. In my area you can rent them for a couple hours at a time.

 

[RandyL]

Consuming that amount of water / coolant should show up on the spark plugs. Pull all 4 of them and inspect for one that has a different look. I have seen what appears to be small crystals as well as an overall different coloration to it in a cylinder burning water. It is best to know all the info you can before any teardown. I could help you spot the problem later on. I pulled my engine and put rings in it. The head was warped .005 between cyl 2 and 3. .005 is the go-no go point so I had it milled flat to avoid any problems. My block was dead level. I pulled the head in the machine and pulled the block later. I slid it all back in at once once rebuilt, using a platform as you mention. It was an experience. I had never worked on a Bobcat before.

 

[Jim A]

Try every head gasket sealer liquid
I had KC seal work on a few engines Blue Devil also..
These products do work about half the time if gasket is bad . No for cracks or a diesel engine .
Worth a try on old machine.

 

[spitzair]

With the amount of coolant we're going through here I don't think one of those liquid sealers is gonna cut it… When you pull your spark plugs out it is very likely one will be super clean, it's essentially getting steam cleaned in there, that cylinder will most likely be the culprit… one other thing I just thought of is maybe the intake manifold gasket is leaking - it has a coolant passage in it going to the head, but that wouldn't explain all the pressure you have in the radiator…

 

[bobcatzack]

The smoke you are seeing from the crankcase breather is either blowby or steam from the coolant leak. More than likely it is steam based on the fact I dont see a big lingering cloud. It looks like steam.
The cylinder head gasket can be done in chassis if need be, but it is a good idea to pull the engine and at least check the rod and crank bearings. coolant in the oil will kill bearings in a hurry. If it has good oil pressure and there is no metal shavings in the oil/filter you are probably OK. Unless you are planning on a overhaul anyway. You should be able to tell if the gasket is blown visually. As stated, it could be a cracked head as well, so take the head to a machine shop and have it checked for cracks regrdless if you see a gasket failure BEFORE any work is done. Overheating can crack heads. If no cracks; clean, surface, valve job and valve seals are recommended. Check cylinders for wear and scoring.
Engine hoists can be rented from a local rental yard in most area's. Call around. In my area you can rent them for a couple hours at a time.

Thank you for the detailed explanations and advise, appreciated! I had no idea a hoist could be rented! I spent half a day today building a platform, disconnecting the engine attachments (which surprisingly went smooth without the need to remove the seat), figuring out how the engine would need to be pulled (ended up using my van to pull it out inch by inch onto the platform). Engine is out now, but I am a bit worried about looking at all the oil and oily sludge that is behind the engine - worse nightmare .. could some of the hydraulic pipes and connections be leaking?!!

 

[bobcatzack]

Consuming that amount of water / coolant should show up on the spark plugs. Pull all 4 of them and inspect for one that has a different look. I have seen what appears to be small crystals as well as an overall different coloration to it in a cylinder burning water. It is best to know all the info you can before any teardown. I could help you spot the problem later on. I pulled my engine and put rings in it. The head was warped .005 between cyl 2 and 3. .005 is the go-no go point so I had it milled flat to avoid any problems. My block was dead level. I pulled the head in the machine and pulled the block later. I slid it all back in at once once rebuilt, using a platform as you mention. It was an experience. I had never worked on a Bobcat before.

Thank you for the valuable advise .. I will get the head checked at a mechanics shop (once I get to the head!). Yes pulling onto a platform was a bit crude method .. I was just by myself so going back and forth between driving the car a bit (to pull) then checking if the engine would not fall off was a bit cumbersome : )

 

[bobcatzack]

Try every head gasket sealer liquid
I had KC seal work on a few engines Blue Devil also..
These products do work about half the time if gasket is bad . No for cracks or a diesel engine .
Worth a try on old machine.

Tried blue devil .. for a few minutes it had given me hope that it may have fixed the head gasket leak .. but the smoky white exhaust cloud reappeared with a vengeance : (

 

[bobcatzack]

With the amount of coolant we're going through here I don't think one of those liquid sealers is gonna cut it… When you pull your spark plugs out it is very likely one will be super clean, it's essentially getting steam cleaned in there, that cylinder will most likely be the culprit… one other thing I just thought of is maybe the intake manifold gasket is leaking - it has a coolant passage in it going to the head, but that wouldn't explain all the pressure you have in the radiator…

Thank you! Yes I will try to make sure and disconnect the intake manifold - see if the gasket/seal is broken.

 

[bobcatzack]

Also check for a cracked head or block.

Yes thanks - I believe after I clean the block will plan to take it to a mechanic shop to have it checked (if all goes well).

 

[bobcatzack]

Yes thanks - I believe after I clean the block will plan to take it to a mechanic shop to have it checked (if all goes well).

With the amount of coolant we're going through here I don't think one of those liquid sealers is gonna cut it… When you pull your spark plugs out it is very likely one will be super clean, it's essentially getting steam cleaned in there, that cylinder will most likely be the culprit… one other thing I just thought of is maybe the intake manifold gasket is leaking - it has a coolant passage in it going to the head, but that wouldn't explain all the pressure you have in the radiator…

Finally have the engine head block visible - the head gasket was definitely damaged (pic attached below), and the video link shows the top view of the engine head, as I love the pistons manually .. I am also noticing of the holes completely sealed off .. perhaps the blue devil coolant sealer I had added blocked the hole instead of fixing the tear in the head gasket? Not sure .. but any advise on how to proceed, and if I should be looking at replacing the pistons etc would be highly appreciated:

 

[dfb]

Definitely a leaking head gasket there, yikes! I would be pulling the oil pan to see the condition of the bearings at the very least. Before taking any of the pistons out pay attention to how far up in the cylinder all the pistons come. They should all be exactly the same distance below the deck surface. A bent connecting rod can easily happen when a cylinder gets the volume of coolant in it your motor was likely going through. A bent rod will be shorter and not come as far up in the cylinder. Anti freeze in the engine oil is very bad for bearings. Lots of small details make for a reliable engine repair, start by checking these items first.

 

[Ster1]

At 100/110 psi compression, you're at the bottom of the range, but you've got acceptable numbers. To get the block bored and an oversized set of pistons in there, you're looking in the area of 2500. A set of pistons is a grand for these engines. You may find a set of pistons that would work like a 1600 Lotus or Anglia on eBay, and those might be cheaper. Just pay close attention to bore size. If it's me, I'm not going to gamble, but that's just me. I'm a dealer for Reliance Power Parts, and can get those parts.

 

[foton]

I did not see any cylinder ridge so have your mech. check the bore and maybe some honing and a new set of rings will do the job. yeah check the crank and bearings since you are right there.

 

[bobcatzack]

Definitely a leaking head gasket there, yikes! I would be pulling the oil pan to see the condition of the bearings at the very least. Before taking any of the pistons out pay attention to how far up in the cylinder all the pistons come. They should all be exactly the same distance below the deck surface. A bent connecting rod can easily happen when a cylinder gets the volume of coolant in it your motor was likely going through. A bent rod will be shorter and not come as far up in the cylinder. Anti freeze in the engine oil is very bad for bearings. Lots of small details make for a reliable engine repair, start by checking these items first.

Valuable advise, will definitely check how far the pistons come up and if they are at each other. Incidentally, a forum member Ster1 happens to be in the area and dropped by to advise me! He indicated by moving the crank shaft that the bearings seem quite smooth, but it doesn't hurt check them out anyways when I get the oil pan removed.

 

[bobcatzack]

At 100/110 psi compression, you're at the bottom of the range, but you've got acceptable numbers. To get the block bored and an oversized set of pistons in there, you're looking in the area of 2500. A set of pistons is a grand for these engines. You may find a set of pistons that would work like a 1600 Lotus or Anglia on eBay, and those might be cheaper. Just pay close attention to bore size. If it's me, I'm not going to gamble, but that's just me. I'm a dealer for Reliance Power Parts, and can get those parts.

It was fantastic meeting you in person, thank you for dropping by to take a look at where things stand with the Bobcat. Thank you too for all the suggestions and assurances that I am on the right track.
Cheers!