Slant Six Forum :: Cooling system problems

Make sure that the thermostat is installed correctly or it will not open preventing any circulation of coolant. The spring side has to be facing into the head in order to sense heat.

I also have to cast a vote for a plugged up water jacket in the head. Remove the block drain plug located just to the left if the oil filter on the side of the block, remove the thermostat and reinstall the thermostat housing leaving the upper radiator hose disconnected. Disconnect the lower hose from the radiator, and flush water through the head with a garden hose using the thermostat housing through the block drain and lower radiator hose until it runs clear.

By removing the block drain, water will flow to the firewall end of the head, down to the block & out the drain. What you did before just let water flow through the thermostat housing, and directly out the water pump never reaching the muck at the other end of the head.

While everything is disconnected flush out the radiator again with fresh water. This may not clean all the build-up out, but will help.

Button everything back up, and refill with 50-50 mix of anti freeze.

Author:	64conv65hard [ Thu Mar 26, 2009 7:41 am ]
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you could also get a mechanical gauge (don't pemananteley mount it) and this way you would know weather the problem is the instrament gauge or the cooling system.

Author:	jason white [ Thu Mar 26, 2009 8:15 am ]
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I agree I like a mechanical gauge over electrical

Author:	BMXICAN [ Thu Mar 26, 2009 9:26 am ]
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Quote: Make sure that the thermostat is installed correctly or it will not open preventing any circulation of coolant. The spring side has to be facing into the head in order to sense heat. I also have to cast a vote for a plugged up water jacket in the head. Remove the block drain plug located just to the left if the oil filter on the side of the block, remove the thermostat and reinstall the thermostat housing leaving the upper radiator hose disconnected. Disconnect the lower hose from the radiator, and flush water through the head with a garden hose using the thermostat housing through the block drain and lower radiator hose until it runs clear. By removing the block drain, water will flow to the firewall end of the head, down to the block & out the drain. What you did before just let water flow through the thermostat housing, and directly out the water pump never reaching the muck at the other end of the head. While everything is disconnected flush out the radiator again with fresh water. This may not clean all the build-up out, but will help. Button everything back up, and refill with 50-50 mix of anti freeze. Damn! I have to drain all the new anti-freeze. I'll give this a go. Thanks everyone for the responses. I really appreciate it. Hopefully I can get this thing to run properly so I can go enjoy it.

Author:	65Dodge100 [ Thu Mar 26, 2009 12:46 pm ]
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I wouldn't put anti-freeze in. Just use plain water until you've tested it and are sure it's fixed. These things sometimes have a way of making you drain it three or four times before you are done. Danny

Author:	bbbbbb9 [ Thu Mar 26, 2009 12:52 pm ]
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I don't know about anyone else but I've used over the counter "System flush/block cleaners" before and it's made things worse. I think the scale breaks loose and then gets clogged in smaller passages. Might be worth your while to pay the bucks to have a shop do an "Indsutrial" cleaning of the block and radiator. Sometimes you save bread by just paying a little more up front.

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Author:	BMXICAN [ Thu Mar 26, 2009 3:12 pm ]
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I already have new anti-freeze in it, so sucks for me because I have to drain it out. If it comes to being rust build up and scales in the block, I'll take it apart and take it to school next week and use the facilities. Anywhere I can save a few bucks helps... Thanks a lot guys! PS: I took out the stat and ran the motor and it didn't get as hot so fast. I'm going to test the stat even thought it's new. Thanks for the tips everyone!

Author:	bbbbbb9 [ Thu Mar 26, 2009 3:20 pm ]
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Save some containers and pour the antifreeze from the engine into it for later use.

Author:	BMXICAN [ Thu Mar 26, 2009 7:32 pm ]
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All I had was an oil drain pan so I used that an don't plan on re-using it so I don't get oil in the cooling system. I found that plug on the right side and removed it. Some rust came out then all brand new anti-freeze and water. While it was out I flushed it with the hose through the radiator for like 5 minutes. The I refilled with water. No stat on and it's still getting pretty warm (210Â°F+ on the gauge). Maybe tomorrow I'll try the stat again. Anything else I should check? Thanks.

Author:	jason white [ Fri Mar 27, 2009 7:30 am ]
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is the engine actually geting hot (can you touch the rad. cap)r ar you just going by what the gauge is telling you

Author:	BMXICAN [ Fri Mar 27, 2009 7:51 am ]
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Quote: is the engine actually geting hot (can you touch the rad. cap)r ar you just going by what the gauge is telling you I'm going by what the gauge tells me. From what I can tell, the engine isn't that hot. I can touch the radiator cap and radiator after it has ran for a few minutes. But I tested two gauges, two senders, all the same (or similiar) readings.

Author:	64conv65hard [ Fri Mar 27, 2009 12:24 pm ]
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what kind of gauge are you using for your testing purposes? i think you should get one of those manual gauges from the auto store, put it in (just the part that goes where the sending unit goes) and then check the manual gauge. it sounds like the gauge in your instrument cluster is off. this will tell you for sure whether or not if it's your cooling system or your gauge.

Author:	oneiros2001 [ Sun Mar 29, 2009 4:32 am ]
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Quote: did you pinch the wire going to the temp sender with the valve cover? BTW anywhere yo live you need a thermostat. That way the coolant stays in the block to absorb the heat. Then in the radiator to disipate the heat. Water quality is another issue. Distilled is a good idea. Sorry to say this but at least for my engine (78 volare supersix) the thermostat is really not that important here in Mexico City and i can tell you this because the thermostat was removed from the engine more than 15 years ago, and the engine works great not a single problem, not a single failure that can be traced back to the removed thermostat, so maybe i am lucky but i doubt that i would be that lucky for more than 15 years, maybe it's because of the weather (average temp for this city is around 75 F not very dry or wet climate).

Author:	00spy [ Sun Mar 29, 2009 5:32 am ]
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I would change out the sending unit , like was said before .It doesn't cost that much , just make sure to buy a good quality one. I swapped mine out with a crappy advance auto one , and when I started everything back up ,the temp gauge slowly almost pegged out. I went out and purchased a standard one , and no problems. Good Luck Dave

Author:	slantfin [ Mon Mar 30, 2009 11:36 am ]
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I had this problem on my 340 for years and kept changing one thing after another. It would run sort of hot and then reach a certain temp and just spike to the max. It turned out to be a played out bottom radiator hose that would collapse even more when it heated up. I put in a new hose, and then made my own internal spring support out of a wire coat hanger. We've been cool ever since.

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