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Post by spud on Jul 25, 2023 17:46:00 GMT -8
The blown headgasket is usually obvious. It kinda depends on how bad its blown but compression in the radiator is usually the problem. If so its likely to have coolant in the cylinder causing white steam from exhaust. Compression in the rad usually manifests as pushing coolant from the overflow, when pressure exceeds cap rating. It will generally push coolant before its hot. Sometimes it will just leak when the power is on, pushing coolant out down the road. Blown headgaskts will cause coolant loss most all the time. Sometimes coolant just goes away and nobody can say for sure where it went🤣. Coolant loss, coolant in the exhaust ,coolant in the crankcase, milky oil, etc…the fan clutch can surely cause problems. It should have plenty of friction when hot. Try a bolt on fan with plenty of blades to see if it helps. A bad fan clutch is pretty easy to find, the fan wont blow much air when you rev the engine hot, it will be quiet too. A working fan is noisey and windy when engine is revved. A slipping fan clutch usually causes problems when vehicle is moving slow or stopped. Some vehicles can get enough ram air to cool efficiently at cruising speeds, some will always need some help from a fan, particularly with air conditioning. If you have a particularly thin cylinder at 7 or 8, you got a fight on your hands cooling that heavy rig. Thats worst case scenario. You can test water pump pressure at the manifold water crossover, it should rise as engine is revved, it may exceed 20 psi, with is good. Your problem is likely gonna be airflow. Cooling problems generally revolve around not enough coolant flow or airflow. Things like timing and a/f ratio are players too, if it runs good and has good power, they are not factors. I dont think you should tear it down. I think if compression is good, spark plugs look good, no metal in the filter, you should focus on keeping it in the chassis.
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Post by landbarge on Jul 25, 2023 17:58:25 GMT -8
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Post by sc397 on Jul 26, 2023 3:29:44 GMT -8
We will have to wait for javtwotone to jump on here to answer those questions. who knows, he may be having a knee replacement going on today..
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Post by javtwotone on Jul 26, 2023 6:00:13 GMT -8
Stupid knee kept me awake all night, so it took awhile to get to work today... Didn't drive it yesterday, instead I pulled the grille to make sure the condenser wasn't plugged up and blocking airflow. I put 3 different stock style clutch fans on the damn thing before I got one that didn't leak and seemed to engage that the right temp. But, he picked it up from me the first time, in early December so no issues going home. He said it overheated on his wife, and that's when the switch to a big-ass electric fan and full shroud happened. The fan kicks on at about 180 and moves some serious air.
From the first post, I really believe the pump is flowing fine, but I've never had a situation where throttling it up with the cap off, made it almost instantly want to overflow the radiator. The level drops, you see it flowing, and within a minute the level starts to increase. So I'm seriously thinking there are two choices. One, highways speeds (todays highway speeds) are too much for a 4500 lbs brick with 3.31 gears to stay cool. What flies in the face of that, is that it still doesn't seem to want to cool back down very well at slower speeds. Two, there is a slight head gasket leak after you start pushing it harder, and once it's hot, it stays hot. I get Spud's comment on the plugs, BUT, I have 7 absolutely identical looking plugs, and 1 with a small amount of white ash. My plan is to drive it again, no faster than about 70 mph and see if it heats up. I was hoping removing the grille would get me access to check for hot spots on the radiator, but the damn condenser is huge..
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Post by Captain Awesome on Jul 26, 2023 9:45:58 GMT -8
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Post by PHAT69AMX on Jul 26, 2023 14:41:41 GMT -8
Wonder if it might be going lean cause that can make it get, hot that and the timing advance, lean, low, and slow can all make a motor run hot can't it?
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Post by spud on Jul 26, 2023 15:06:27 GMT -8
You might be on the right track thinking that the 4500 pound brick as it currently exists is just pushing(the current cooling system) too hard. In as much as its creating more heat than the cooling system can rid itself of. Aluminum heads and an overbored 401 block - might be- compounding the problem. I still say try it without the hood. No its not a fix, but it does say increased airflow helps or not. You made an interesting observation about coolant overflowing out the fill neck when you rev it. Now i’m not sure if any cooling system would do that ( or not) but it does kind of sound like the pump is pushing coolant, but it doesnt say the suction side of the pump is drawing it through the rad core. Could there be restriction somewhere? In the core? In the lower hose? Or maybe the coolant is just taking the path of least resistance and coming out the fill neck because there is no cap to stop it. I dunno bout that. Does it have a good thermostat? I think i would give that a thorough test with hot water and a thermometer. Just to be sure its behaving as expected. Something i have done through the years working on trucks is this. It seems like a hassle , and it is, but i have gone to the extremes of putting a two temp gauges in the top and bottom hoses ( or tanks) of the system. Using two identical “ manual” water temp gauges. ( you know, stuart warners with capillary tubes and bulbs) and doing what we call a “ cooling system audit” , in which we put the truck through its paces and monitor the top and bottom tank temp. A good system usually will cool 5-10 degrees less in the bottom tank. If it dont the radiator is not adequate, or airflow is not adequate, its a elaborate way of ruling out the engine as a problem. I have gone so far as to continue trsting with two low pressure “ compund “ gauges that read vacuum to about 25 psi. Run the truck and get readings on them, and the wider the readings the poorer the radiator flow and function is. Sure its a hassle, but sometimes it gets done. Horsepower makes heat, if you got too much heat, well, you gotta get rid of it the most practical way you can. It might be more air through a given rad. It might be more rad area. It might be more rows. As long as the pump is making good pressure and the thermostat is fully open, your gaskets are good ( blown gaskets and or cracked heads ALWAYS overpressurize the system and this shows on a system pressure test with a pressure gauge, if you dont overpressurize the cap, the gaskets are ok) if you have these three things, you engine is GOOD. And your cooling through the rad ISNT GOOD ENOUGH. If it wont cool down at idle with zero hp being made, and the fan is blowing your hat off… i’d say you dont have enough rad, or rad FUNCTION…
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Post by 69Rebel on Jul 26, 2023 15:13:00 GMT -8
That's good info spud. My Chevy (one ton) does almost the same thing. It's fine running empty, or with a thousand pounds or so in the bed, but pulling a trailer, it will slowly heat up, and kind of do it in a cycle. One difference is that it cools off rapidly when I slow down. I figger it's running a little lean.
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Post by spud on Jul 26, 2023 15:25:02 GMT -8
By gum if you think its lean you should find out for sure with an a/f gauge. Thinking is your first step. Knowing is what you really want. When your sure of things you have accomplished actual troubleshooting. Troubleshooting in its essence is finding out what is good or bad for true. Guessing is what it is. Find out what is good, eventually you will come to the trouble on “ the last check” you want a blind cheap guess? Run some fuel system cleaner through your injectors. It might fix things. You will know you did some good when it runs stronger, gets better mileage and cools better. If nothing happens at least you didn’t spend much money. I run fuel system cleaner in every tank becuz i get about 25 more miles from a tank. So its like getting about a gallon of gas “ more” in a 16 gallon tank. Kind of a lateral move for the money but oreillys sells cleaner for 4 bux i tell you another thing, you should flush the hell out of your cooling system and fill it with new coolant. Every spring . Because poor coolant plugs up rad cores. It never sleeps. Its always there. Fucking you over. You cannot over maintain a cooling system. Aluminum rads are worse thay brass about plugging from corrosion and deposits from neglected coolant. Bright green is fine. If it has that yellow green tint it us BAD.
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Post by 69Rebel on Jul 26, 2023 16:24:25 GMT -8
Yeah, flushing the cooling system was going to be my first step. It has a brand new AVS-2 carb, that hasn't been tuned to the motor yet. It's nice that AFR meters are kinda cheap these days. Takes a lot of the guesswork out of tuning. I really need to get one.
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Post by spud on Jul 26, 2023 17:49:31 GMT -8
Oh i thought you had factory efi. You cant beat a good a/f ratio monitor. I love my innovate motorsports LC-2. Summit price 189$ And it has interface for datalog and efi systems or ecu’s and stuff i dont really need but its cool it works with a bunch of other hitech nonsense if i ever go that direction… which i probably wont but times are changing quick with digital carb enhancement systems like the “ carb cheater” system we were discussing in the carb tuning topic. As a matter of fact, YOU! Should consider a carb cheater on your carbed tow rig! Every bit of mileage counts.
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Post by 69Rebel on Jul 26, 2023 19:56:27 GMT -8
My 3500HD has the 454 with factory TBI. So far, no heating issues with it. The '88 one ton has a carbed 350.
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Post by javtwotone on Jul 27, 2023 3:33:14 GMT -8
Storms last night, so no tests. Jeep doesn't have aluminum heads, not sure why SC397 thinks it does cuz you know .. he built it.. Apparently it has 304 heads.
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Post by spud on Jul 27, 2023 4:24:29 GMT -8
304 heads? Maybe thats why it doesnt run like a 401?
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Post by javtwotone on Jul 28, 2023 3:55:43 GMT -8
I can't get the stupid chart to post up, but they're modified 304 heads with the bigger valves from the 360/401 heads.. SC397 is off playing with himself in Kenosha, so he can't chime in. I ran this thing through plenty of gas last night. Drove it between 65-68 mph until it AGAIN got hot. Even at 50 mph, once it was hot, it stayed hot. Idled it with the A/C on in 88 very humid degrees. Stayed right at 220 on the gauge. After awhile, I popped the hood to try and check some temps on the radiator, and of course my temp gun started fucking up.. Temp had dropped to 215 during that fiasco, closed the hood, and it stayed at the 215. Let it sit there for awhile and nothing changed. Throttled it up for less than a minute, and it was back to 220. Leave it alone again, and it stayed at 220. Brought out my shop fan, bigger than a house fan but not a huge industrial thing either. 2 degree drop from the 220. Again, left it alone and it stayed at 218. Hood up again, and back to 215, but no lower. Close hood, turn off shop fan, and stayed at 215. Throttle it to get it back to 220 and turn off A/C. Maybe 1 degree drop? at this point my eyes are crossed looking at the damn gauge for so long. If the storms hold off tonight, I'm going to try to confirm my earlier finding that if I just idle it from cold with the A/C on and no reving it up, it will sit there at around 190 and not go up. Supposed to be mid 90's and 105 heat index. Not sure what that will tell me, but just collecting data at this point. Also going to dig through my junk for a mechanical gauge.
Also, it does have the opening next to the battery for the cold air hook up.
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