Hot 59AB

western77

western77

Senior Member
I have 59ab in a 1941 pickup. Bought it in 1984. The engine is a 1953 mercury, all standard bore, mains and rod bearings. It always ran on the hot side. I put in thermostats, washers to slow the coolant, steam cleaned out the block and heads, nothing helped. I gave up on it. It sat in the barn until this winter with nothing more done to it. This spring I put in new valves,guides, springs, lifters,honed the bores and new rings, recored the radiator with over size core, rebuilt the 94 carb, new fuel pump and regulator, 180 thermostats, 50/50 antifreeze, resurfaced heads, and gaskets. It has duel exhaust with glass packs. I am running 15-40 Mobil oil with added zinc. It runs great, but will " over heat" in about 12 minutes. At that time the temp. will be 207* and climbing. The radiator will take about 25* out top to bottom. The dissy is the ford loadmaster with only vacuume advance. I started with the timing at the dimple first but have gone to 8* BTDC now. Nothing seems to work. I don't know what to do next. Any suggestions would be helpful. Thank, JB
 
I know you had the block steamed, but did anyone really work on the rear area around the cylinders? There can be an unbelievable amount of stuff in there. I took some long drill bits, welding rod, metal coat hangers, etc. and worked on it several times and each time more crude came out. Mostly left over casting sand and casting wire. It just keeps coming and coming out!! This was after this block had been previously rebuilt and the block cleaned and run for years. I took the engine apart for another rebuild and had the block tanked and sprayed. The sand and wire is really packed in there and years and years of rust and stuff in the coolant system just packs on top of it. You might be surprised at the amount that can come out of the back of these blocks.
 
The most common source of overheating, once you've eliminated a clogged radiator as the cause (as well as all the other work you've done) is a cracked block. The most common place for a crack to occur is between the exhaust valve and the cylinder wall on the "siamesed" exhaust ports (cylinders 2/3 and 6/7). Time to take the heads off and examine.
 
Is the advance working in that load-o-matic? Often the diaphragm fails, and then no advance; your timing is retarded at anything above idle. Retarded timing is a sure-fire recipe for overheating! Unless you have the original carburetor, you will not have the proper advance rate, either.
 
Might be worth the chevy distributor mod, would gain a lot of additional benefits. Just a thought.
 
You can not test for heating problems sitting in the drive way. Even driving the same conditions don't always exist. The best test is with a large house type fan AGAINST the center of the grill. First remove the washers and stats. Never put washers in these engines. Stats don't do anything to help cooling they only restrict the flow and make it run hotter. After you get the problem solved then try the correct type stats that don't restrict the flow. Make sure your 4 lb pressure cap works, to work the rubber end must seat against the washer like seat about 1" down in the filler neck. Most caps don't hit that seat so you don't have a pressure cap. Start the engine with the cap OFF and add coolant as it warms up. Fill it up into the filler neck to the seat and put the cap on. With a hand held laser pointed thermometer check the temperature on the neck of the heads just below the radiator hoses. You have to hold the gun the same distance and from the same angle with the laser spot hitting close to the same area every time. Take the temperature at the start and every 5 minutes writing the temps down. Do this until the temperature gets to 205, if it gets over that with a good fan you have a problem and we will address that later. The temperatures you get with this test is the temperature you will have on the road at 45 plus MPH. If coolant comes out the over flow at 205 your pressure cap isn't working or not seated. G.M.
 
Check with a radiator shop as to whether they can do a combustion gas test on the cooling system, I have used various methods to check the cooling systems , most all are a little risky to ones safety if not done correctly, you also may have a waterpump impeller loosening up as the engine warms, I had one of the waterpump impellers
loosen on a rebuilt pump , this was a rare occurrence for me I think it was inferior parts, the shaft wasn't machined correctly .
 
40 Deluxe said:
Is the advance working in that load-o-matic? Often the diaphragm fails, and then no advance; your timing is retarded at anything above idle. Retarded timing is a sure-fire recipe for overheating! Unless you have the original carburetor, you will not have the proper advance rate, either.
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BINGO !!!!!
We didnt say it was a working loadamatic?? If the vacuum diaphrahm isnt working the timing would be way retarded and run hot every time.

Try this just for testing , advance the distributor at idle quite a bit ( 20-24 degrees etc) and test drive the vehicle if the engine cools down thats your problem......dont leave it with that setting as started might kick back a little bit...........
Is the carb signal there for the advance ???? Is the diaphrahm working ????
 
I have tested the advance with increased rpm and the diaphragm is working and advancing the timing. The vac diaphragm is connected to the 94 carb at the vac port on the side. The water pumps are moving a good amount of water up to the radiator. I can not say the impeller is not slipping, but there is a lot of water coming into the radiator. When I steamed out the block I worked extra hard in the back of the block and you are right, there was a lot of sand and wire that came out. I worked over 30 minutes with live steam. I will take the stats out and see the difference with the fan test. No washers in since 1986! No leaking out the overflow at 207*. JB
 
Here's a good tip the water hole size's in the head gaskets might be TO small thus allowing the coolant to become super heated by the exhaust ports. Also the 50/50 coolant mixture will not help reduce temp but of course it will help with a freeze up. The best coolant is just plain water adding antifreeze actually reduces the amount of heat it will dissipate. If you try just water your temp should drop 10 degrees. At least that's what I have experienced during my testing of cooling modifications on my super charged flatheads.
 
western77 said:
The jet size is .045 I believe.
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Stock on an 8BA would have been a #51, you are mighty lean for a Merc.

BTW, it's confusing that the title of the thread is "Hot 59AB" but your engine is an 8CM, late model Merc. Quite a few differences.
 
GET RID OF THE WASHERS YOU PUT IN TO SLOW DOWN THE COOLANT. Skip pumps and most of the new pumps pump the water faster than the stock pumps. The washers are an old wives tale. Especially if your timing and advance is working. i also put high flow thermostats in
 
You are correct, I don't know what I thinking, it is an 8BA. Thanks. I will pull a jet today and check for sure what size they are. There are no washers in the system since the freshing of the engine just 180 stats. The plugs good ok but have not ran it on the road for any length of time. I put the graphite kevlar head gaskets made by Best gasket co. They looked like a very good fit. The reason I went with antifreeze is the higher boiling temp. What temps are you guys running your flatheads at down the road and at an idle?
 
man i know what you are going through same deal mine was the timing sent dissy to bubba drove to work today 82 miles ran great at 175 0n stant love it:)
 
western77 said:
I have tested the advance with increased rpm and the diaphragm is working and advancing the timing. The vac diaphragm is connected to the 94 carb at the vac port on the side. The water pumps are moving a good amount of water up to the radiator. I can not say the impeller is not slipping, but there is a lot of water coming into the radiator. When I steamed out the block I worked extra hard in the back of the block and you are right, there was a lot of sand and wire that came out. I worked over 30 minutes with live steam. I will take the stats out and see the difference with the fan test. No washers in since 1986! No leaking out the overflow at 207*. JB
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Before you put the cap on as the engine warms up with the water filled up into the filler neck if there is a compression leak you will see bubbles in the water. ALL of these engines should have a large bottle of radiator and block sealer to seal any small leaks. Is there any black drops of water coming out the exhaust when the engine is started? G.M.
 
western77 said:
You are correct, I don't know what I thinking, it is an 8BA. Thanks. I will pull a jet today and check for sure what size they are. There are no washers in the system since the freshing of the engine just 180 stats. The plugs good ok but have not ran it on the road for any length of time. I put the graphite kevlar head gaskets made by Best gasket co. They looked like a very good fit. The reason I went with antifreeze is the higher boiling temp. What temps are you guys running your flatheads at down the road and at an idle?
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You said 59 engine, the place to check cooling on an 8 BA is on the top of the goose necks. G.M.
 
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