Coolant Blow-out
06-23-2008, 10:32 PM
#16
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You might consider borrowing a cooling system pressure tester. Many parts places will loan you one if you leave a deposit. It lets you pressurize and check for leaks without risk of burning your fingers.
A possible problem only briefly mentioned is the reservoir itself. The tired old plastic is known to fracture with age and the high-temp service. Leaks are tough to impossible to locate because of the location. It's worth a look. And as Sean pointed out, that bottom hose is a chore to change, much easier as part of a reservoir replacement effort.
A possible problem only briefly mentioned is the reservoir itself. The tired old plastic is known to fracture with age and the high-temp service. Leaks are tough to impossible to locate because of the location. It's worth a look. And as Sean pointed out, that bottom hose is a chore to change, much easier as part of a reservoir replacement effort.
06-23-2008, 10:39 PM
#17
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Could be a cracked reservoir. Before you dig into it pressure test the cooling system. You can buy a cheapie pressure tester for ~$20 at NAPA, or you can cobble together a schrader valve and gauge with couple of tees and barbs and a short section of hose, install this on the top of the radiator where the bleed hose attaches. Pump to 15 psi (~1 bar) and see if it leaks down. DON'T pressurize higher than the cap rating, except briefly to ensure it releases pressure. Don't want to blow anything up. 
[Edit]I see bob beat me to it...
[/Edit]
[Edit]I see bob beat me to it...
[/Edit]
06-26-2008, 12:01 AM
#18
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OK - now I feel like a complete idiot. I was all ready to hunt down a leak and on that I got great feedback from you guys - many thanks. Now for the admission.... I decided to just do a basic check on the fans and hard wired them to ensure they were working OK. Alas!! - I found that the in-line 25A fuse had blown in the main electric fan!!!! No wonder I overheated!! No main fan! So then I was on a quest to find out why the fuse would blow. My hard wire test showed the front fan direction makes it a PULL fan which draws air away from the A/C rad. Surely this is incorrect??? Logic says it should PUSH the air thru the rad front to back. Unless I hard wired it incorrectly and in doing so made it go in the wrong direction, would having the front fan PULL air away from the rad cause the rear fan to work harder and blow the fuse? Anyone care to comment on my logic?
Cheers
Cheers
06-26-2008, 12:18 PM
#19
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Just thought that I'd post the results of my leakage. It was the plastic reservoir bottle that has a small crack. Ordered replacement from 928Intl
Hey Dr. Bob, how are things in Old Miss
Hey Dr. Bob, how are things in Old Miss
06-26-2008, 09:12 PM
#20
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Larry--
Things are hot and humid, not as hot as when I left Cali but for sure more humid. It takes the rental car a long time to cool the car down with all that humidity. I leave the hotel AC cranking, hoping to un-limp a few dress shirts by dehumidifying the air a bit, but they get soggy as soon as I go outside so what the heck. I should be back home in a day or two.
When you get the reservoir, have Jim ship ALL the small coolant hoses and a new heater valve. There are a couple hoses that are a chore to change with the reservoir in place-- Might as well change them when you have the reservoir out. Get a new cap too, and a couple washers for the block galley bolts. If the big hoses are older, might as well replace them too while all the coolant is drained out.
A new reservoir needs to move onto my to-do list. I need to do the intake refresh sometime this year so the reservoir makes sense while that and the cam covers are off for refinishing. I did all the hoses when I did the timing belt last.
Things are hot and humid, not as hot as when I left Cali but for sure more humid. It takes the rental car a long time to cool the car down with all that humidity. I leave the hotel AC cranking, hoping to un-limp a few dress shirts by dehumidifying the air a bit, but they get soggy as soon as I go outside so what the heck. I should be back home in a day or two.
When you get the reservoir, have Jim ship ALL the small coolant hoses and a new heater valve. There are a couple hoses that are a chore to change with the reservoir in place-- Might as well change them when you have the reservoir out. Get a new cap too, and a couple washers for the block galley bolts. If the big hoses are older, might as well replace them too while all the coolant is drained out.
A new reservoir needs to move onto my to-do list. I need to do the intake refresh sometime this year so the reservoir makes sense while that and the cam covers are off for refinishing. I did all the hoses when I did the timing belt last.
06-26-2008, 10:11 PM
#21
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Larry--
Things are hot and humid, not as hot as when I left Cali but for sure more humid. It takes the rental car a long time to cool the car down with all that humidity. I leave the hotel AC cranking, hoping to un-limp a few dress shirts by dehumidifying the air a bit, but they get soggy as soon as I go outside so what the heck. I should be back home in a day or two.
When you get the reservoir, have Jim ship ALL the small coolant hoses and a new heater valve. There are a couple hoses that are a chore to change with the reservoir in place-- Might as well change them when you have the reservoir out. Get a new cap too, and a couple washers for the block galley bolts. If the big hoses are older, might as well replace them too while all the coolant is drained out.
A new reservoir needs to move onto my to-do list. I need to do the intake refresh sometime this year so the reservoir makes sense while that and the cam covers are off for refinishing. I did all the hoses when I did the timing belt last.
Things are hot and humid, not as hot as when I left Cali but for sure more humid. It takes the rental car a long time to cool the car down with all that humidity. I leave the hotel AC cranking, hoping to un-limp a few dress shirts by dehumidifying the air a bit, but they get soggy as soon as I go outside so what the heck. I should be back home in a day or two.
When you get the reservoir, have Jim ship ALL the small coolant hoses and a new heater valve. There are a couple hoses that are a chore to change with the reservoir in place-- Might as well change them when you have the reservoir out. Get a new cap too, and a couple washers for the block galley bolts. If the big hoses are older, might as well replace them too while all the coolant is drained out.
A new reservoir needs to move onto my to-do list. I need to do the intake refresh sometime this year so the reservoir makes sense while that and the cam covers are off for refinishing. I did all the hoses when I did the timing belt last.
I'm going to miss VCR, but had lunch with Rolf today and I think he might be going. See you when I see you
07-01-2008, 04:27 AM
#22
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I would like to update my info on my overheating problem in order to get some more help from you all. My front A/C fan is actually a push fan - I had my wires crossed when I did a hard-wire test. 
Sorry for the red-herring.
So I went ahead and replaced the in-line 25A fuse and topped up with coolant - started her up - no leaks!! However, on warming, main fan did not come on - the fuse blew again. So now I am on a quest to find out why the 25A fuse would blow. A/C fan came in when temp increased, so I assume that is working OK. Both fans are aftermarket. Any suggestions on why the (main) fan would draw more current and blow the fuse?
Brand new main fan - replaced PO's when the wires melted on that one. I never checked when I hauled it out and discarded it, but now I am starting to think that the cause of its demise was because the PO may have just put in a heavier fuse - I am sure he had the same problem as I am having.
Anxious to get this fixed asap, as my driving season up here is short! Any suggestions on what I could check?
Cheers
Sorry for the red-herring.
So I went ahead and replaced the in-line 25A fuse and topped up with coolant - started her up - no leaks!! However, on warming, main fan did not come on - the fuse blew again. So now I am on a quest to find out why the 25A fuse would blow. A/C fan came in when temp increased, so I assume that is working OK. Both fans are aftermarket. Any suggestions on why the (main) fan would draw more current and blow the fuse?
Brand new main fan - replaced PO's when the wires melted on that one. I never checked when I hauled it out and discarded it, but now I am starting to think that the cause of its demise was because the PO may have just put in a heavier fuse - I am sure he had the same problem as I am having.
Anxious to get this fixed asap, as my driving season up here is short! Any suggestions on what I could check?
Cheers
07-01-2008, 02:49 PM
#23
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Start off with a basic ohm meter check of the wiring and the fan motor itself. Checking for shorts to ground in the wiring, and the basic internal resistance of the fan motor. From the fan motor resistance, you can decide if the wiring is adequately sized, and if the 25A fuse is correct for the application. Verify that all the connections are sound, including the ground connections. Make sure any fan relays are working correctly, and are sufficiently sized to meet the fan motor load. Cheap off-brand relays under high load are hidden disasters, so you may want to go shop for relays rated at 40 amps rather than the common 25-30 ratings just to be sure. Then go on to Stupid Stuff. Is the fan able to actually spin under all conditions? Stupid Stuff like that.
