SuperMotors.net Forums
MassP71
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• Waltham, MA, USA |
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• Registered on 5/27/2013 |
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• 1 post |
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 Posted:5/27/2013 14:43 |
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Hi all,
1999 P71, 90K Mi. overheating
Steps I have taken,
Replaced thermostat, brought car to mechanic who flushed radiator,
Then replaced cooling fan relay & cooling fan fuse,
Then replaced cooling fan motor.
I have not seen any leaks, no antifreeze in oil or around spark plugs. I still have to pull a couple of plugs and check for fluid indicating a cracked manifold.
Sorry about the following lengthy history in advance but I thought it may assist someone who may be able to help me diagnose this issue:
I have a 1999 Crown Vic. (90K Mi), I've owned her for two years, that overheated after a monumental snow storm this past February. The day before car was running for about two hours in my parking spot while I shoveled out of the mess. Traffic was very slow the next day and I put a heavy load on engine going up hill after about half an hour ride when overheating occurred, analog display shot up from normal operating temperatures of 1/3 to 1/2 way up to overheat and symbol lit up (not flashing) . I found a safe place and pulled over.
Coolant level was fine, no leaking antifreeze, system seem pressurized, upper & lower radiator hoses felt hot so I believe coolant is circulating OK, and fan was blowing when car was overheating. I figured day after huge storm AAA would take too long to tow me so I sit with car for an hour or so then drive home, running a little rough so thinking fail safe may have kicked on alternating cylinder operation although the check engine light didn't light up nor did overheat symbol flash.
Inspected car, nothing seems wrong & can't get car to overheat again. I'm thinking ice or snow was blocking radiator or thermostat shot or frozen or something. Drive car normally, about 20 miles each way to/from work, city then highway, with traffic for about half an hour forty minutes each day without recurrence until a couple weeks ago.
After 20 minutes on ride home on highway I hit traffic, car overheats, display shoots up from normal operating temperatures of 1/3 to 1/2 way up to overheat and symbol lights up (not flashing), I immediately cranked the heat, temperature gauge drops a little so symbol not lit up I pull over, open hood see fan motor running high speed, no apparent leaks so I shut off car, wait an hour and limp home again.
I replaced the thermostat, let car warm up to 1/2 way on gauge but radiator fan not engaging, coolant flows when car given gas. Turn on A/C to max cooling and fan kicks on for about 6 seconds and turns off and doesn't come on again. Coolant looked dirty so I bring to a service station the next day who flushed the radiator. I told them about fan not turning on I believe they pressure tested system and he told me they jumped fan motor which went on but blew a fuse which he replaced, no cost.
I replace the cooling fan relay & 30 amp cooling fan relay fuse. The fuse they put in had a solid aluminum casing which I couldn't tell if it was blown and fuse was 3 - 4 bucks. I run car till temperature gauge gets to 1/2 way mark but radiator fan not engaging. I'm now thinking fan motor may be bad. This P71 came from an auction in Florida three years ago, I've owned her for the last two years and from maintenance records I see car was driven for several years, then last five years in service had about 1000 miles a year on it until sold at auction so fan motor may have had lots of use idling in Florida heat.
Drive car to work every day till next paycheck but car overheats on highway, after hitting slow moving traffic jam so I call AAA and get towed home last nine miles or so. I am convinced I figured this out so next day I replace fan motor, check pigtails which were not oxidized and wires didn't look burned, run engine till 1/2 way up gauge but fan motor not kicking on, turn A/C to max & nothing. Check 30 amp fuse which is blown so I replace it. Rinse, repeat and same result fan motor not engaging now but fuse did not blow. Which brings me to today.
I don't have a volt meter to check relay and could probably figure out how to jump fan motor to check but I'm at the point where I may just figure out how to connect toggle switch to radiator fan and manually switch on when needed.
I think the only thing I haven't replaced is the coolant sensor by the thermostat but I don't think that's the problem. I am hoping I haven't replaced a part with a defective part or somehow caused more of a problem. I have researched on line forums, manuals and videos before each replacement and believe I did a good job replacing parts and that all replacement parts are good. I have worked on my past cars so I'm not too green.
Should I bring this to a dealer or mechanic to run electrical or computer diagnostic tests? Is that something they do? I don't have unlimited funds to have a dealership start replacing coolant system piece by piece and thought I could do this without too much trouble but I am stumped.
I am hoping this is something someone has heard of before and can help with,
David |
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Posted:5/27/2013 18:05 |
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A headache some CVPIs have is the water pump. Hidden there in the engine, most people don't think about it. One of the reasons the manufacturers tell you to use distilled water (like in the battery) is the minerals tend to build up after a time. It is possible the water pump has started to build corrosion slowing the flow of water.
I've seen water pumps go out at 20,000 miles and others last over 100,000 miles. Years ago the shop would check the concentration of antifreeze in the cooling system, which gave them an idea of whether corrosion was building or not. Now you go buy those "lifetime" coolant fluids and forget about it.
You say it is overheating because the gauge tells you so. Is it boiling over and flowing coolant out of the catch reservoir? The gauge or the sender could be gong bad too. Mine stays at about the 2/3 mark after the engine warms up. I added an electric temperature gauge and found it was running about 210 degrees HOT.
The fan could just have a bad connection someplace down the wiring so it is not sending a signal to turn on. Wiring problems are a PITA to trace. I'm trying to remember if the fan gets its signal directly from the PCM, which gets the temperature from a sender. I think some CVPI have two senders on the water crossover by the thermostat; one for the gauge and one for the PCM.
So you could replace the Temp sender like you said, and it may fix it. If yours has two senders, replace them both. They are about $15 each. You could replace the water pump, and it probably will fix it.
I wish you plenty of luck trying to figure this out. Let us know what you do find.
*******************
PROUD MEMBER of www.crownvic.net
It's just a SUPER-DUTY Mustang GT Sedan. 198K miles and still rolling HARD.
1997 Crown Victoria P71 SVT *** ex-US Marshall service (the CAR)
STOCK?? I bet it was modified. 
13.26 @ 107.24 MPH 1/4 mi w/ me, tools, & full tank of 93 octane
I added CAI, NICHE 19 X 8.5 " wheels with 245/45ZR 19 rubbers, and completely rebuilt the front end with poly bushings, Kooks headers, 2 1/4inch exhaust, TCI 2200-2400 rpm Stall converter
.PLANS:: engine upgrade, 5.4L 2v stroker, rebuild interior in leather w/ buckets, thinking about turbos
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Posted:5/28/2013 08:24 |
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+1 on the water pump and sensors
With the fan not kicking on that would tell me that the temp sensor responsible is not tripping and most likely bad. Also the dirtier your coolant when you flushed the more likely you have corrosion in the water pump. |
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Hammerman63
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• Ayer, MA, USA |
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• Registered on 6/26/2013 |
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• 4 posts |
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Posted:6/30/2013 17:20 |
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Probably radiator plugged between condensor and radiator. Pull radiator and condensor apart and blow out the radiator from behind. Very common problem on police cruisers. |
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