94 3.0 200,000+ miles, Got it for a nice price with about 180,000 miles, was driven to work 35-40 miles daily on highway by PO's wife, and was well maintained. Had it for about a month, and my wife drove it hot, (fan clutch failed) and cracked a head. I had the good head rebuilt, and bought a rebuilt head from a guy my machine shop recommended. Had intake manifold cleaned, installed new fan clutch, waterpump, thermostat, head gaskets, plugs, wires, cap/rotor, oil pressure sending unit, heater hoses, new radiator cap, new fuel cap, fuel filter, air filter, pcv valve, 02 sensor, vacuum hoses, shocks, and sway bar link bushings...whew! New radiator, tranny filter and gentle flush is next project, then i gotta open the differential and stop the slow leak around the cover. My radiator has pinhole leak above drain valve, but needs replacing, because after she ran hot, I hurt my back, and couldn't work on her for about 6 months, and the radiator rusted up.
A couple of days ago, I flushed a bunch of rusty gunk out, and replaced coolant. Now, at some point after she warms up, my temp gauge will drop from "r" down to the "n", and back up again. I then noticed my upper radiator hose was being sucked flat, and I believe it corresponds to the gauge dipping down and back up. The hose is old, and needs to be replaced.

Thermostat clogged from flushing? Weak upper hose? Clogged radiator?
Any thoughts?

I also have the RABS light, and CEL was on when I bought it, gotta get codes pulled, or just buy a scanner.

Overall, it is a great vehicle, and a pleasure to drive. The interior is perfect, and it has the coldest AC i've ever had in a vehicle.

T

 

I would definitely replace your thermostat based on your scenerio. Rust deposits, specs, setiment, etc can all be considered "foreign matter" in your cooling system, which can cause the stat to open slow, close slow, or stick open or fully closed (the later rarely occurs. If it does fail, the majority of them stick open, which causes cold start, emissions, rich problems. Running to rich in this scenerio will quickly ruin the o2 sensor, and eventually the cats. I would replace the thermostat as soon as possible. Flushing with a "T" in the heater hose is good for a at home flushing. You can also remove the stat, then put the top hose on, and continue for a good 15 minute flushing cycle. Then, when you're convinced everything is flowing clear, install the new thermostat, with the correct temp, usually 193-195 degrees. Always use distilled water, soft water, but never tap water, unless in an emergency. Last, do nut run over 50% coolant. too much antifreeze can cause problems as well. Good luck. ED
PS Look at the color and condition of the insides of your radiator and heater hoses. That can give you clues, as to the condition of the cooling system. If you see brown rust color inside the hoses, consider changing all of them ASAP. There is a product called "NoRosion" that works great in clean cooling systems. It is burgundy red in color (like red wine). Just don't drink NoRosion when you are hungry, and having a delicious spaghetti dinner!

 

As for the flat hose that is the sign that it needs replacing because eventually the mesh frame that keeps the hose round breaks down and the rubber itself becomes too flexible and gets pulled into the coolant stream crushing it.

The local Ford dealer might charge you an arm and a leg but I was able to get an upper rad hose from fordparts.com for $21.28 + Shipping. I would stick with stock on the hoses since you can't determine the quality of those aftermarket hoses.

Don't forget to buy some screw-type clamps for the hose and don't try to reinstall those factory squeeze clamps since they dig into the rubber of the hose and cause more harm then they're worth.

 

Hi Mormakil:

I don't want to alarm you, but the guy who replaced your water pump might have put in the wrong one. I believe that on the 3.0L, there are two different water pumps. One is for '94 and earlier, one is for '95 and later. I believe the direction of rotation is different, due to the fact that '95 and later 3.0L uses one single serpentine belt for everything, and the water pump rotates counter-clockwise looking in from the front. On the older 3.0L, there are two drive belts, and the pump rotates clockwise.

As a result, your suction side is now the upper hose instead of the lower hose as it should be. The upper hose should never see suction, unless you shut the engine off and let the van cool down, during which everything will see vacuum.

I'm not saying that's what actually happened, but given the information you post, it's highly likely.

 

Thanks for the replies. Actually, I did the work myself, except rebuilding the heads, and I did not have the hose problem until a couple of days ago. The waterpump has performed perfectly (about 5 months) and my hose and gauge symptoms only showed up a couple of days ago after coolant flush and refill. I have a single serpentine belt and another for power steering pump. I know my radiator is too far gone and needs replacing, as do the hoses. I have never seen a hose flattened like that before, and now I'm pretty sure my thermostat is clogged or stuck. I guess my gauge jumps around because the coolant flow is restricted, and the temp drops on the gauge when there's no coolant flowing past the temp sensor. I guess what puzzled me was the gauge dropping and rising back to normal so quickly. I didn't think the sensor was that sensitive. Plus, the wiring on the temp sensor plug is not in the best shape. That's where I started this chase.

Also, where are the ground strap locations? I have one I wasn't sure about when I re-assembled after the head job. Passenger side, rear of engine, I secured it to the exhaust manifold, not sure if that was correct, or if it would matter.

Final question, what is the small cylinder in-line with PCV valve vacuum hose? It has an electrical plug on one end, and a T-fitting on the other for vacuum hoses. One end to PCV valve, and other to charcoal canister, if I remember correctly.

Thanks,

T

 

That is the Canister Purge Solenoid. It has nothing to do with your cooling problem. It's always a good idea to replace the thermostat periodically, so it won't hurt.

 

It could be the temperature gauge is jumping because somewhere on the wire leaving the temp sender unit the insulation is chipped off and coming into and out of contact with some metal component as you drive.

It could also be a faulty sender unit but take it one step at a time and solve the bigger problems first and see what happens with the gauge.

 

mine moves suddenly as well. on cold mornings it will suddenly jump when the thermostat opens. so it might just be what you think it is, a sensitive gauge. no harm in checking the wiring though. I did find an unrelated problem while checking mine, and it's cheap insurance for your peace of mind.
the flattened hose sounds like a restriction in the system blocking coolant flow, combined with soft, degraded hoses. I'd be suprised if it's the thermostat though. when mine stuck closed my upper hose had actually ballooned somewhat under the pressure, and the temp would start towards overheat VERY quickly. I would suspect something in the rad first, especially if it's showing the signs you described.

 

Morm,
sounds like you have an air lock or air pockets in your cooling system coolant, probably induced by the flushing several days ago. as steam bubbles pass thru top hose, they cause a rapid pressure change and hose collapse

ECU codes on '94 can be read by jumpering 2 connectors in OBDI plug under hood...search Aero forum for directions

see below for air purging

emailed RABS from Ford Aero manual, post too long

from Ford Service manual
Cooling System, Draining, Filling

WARNING:
NEVER REMOVE THE RADIATOR CAP UNDER ANY CONDITIONS WHILE THE ENGINE IS OPERATING. FAILURE TO FOLLOW THIS INSTRUCTION COULD RESULT IN DAMAGE TO THE COOLING SYSTEM OR ENGINE AND/OR PERSONAL INJURY. USE EXTREME CARE WHEN REMOVING THE RADIATOR CAP FROM A HOT RADIATOR. IF POSSIBLE, WAIT UNTIL ENGINE HAS COOLED, THEN WRAP A THICK CLOTH AROUND THE RADIATOR CAP AND TURN IT SLOWLY TO THE FIRST STOP. STEP BACK WHILE THE PRESSURE IS RELEASED FROM THE COOLING SYSTEM. WHEN YOU ARE SURE ALL THE PRESSURE HAS BEEN RELEASED, PRESS DOWN ON THE RADIATOR CAP (STILL USING A CLOTH), TURN AND REMOVE IT.


Draining

1. Shut off engine (6007) and allow to cool.

2. Remove the radiator cap (8100). Refer to above warning.

3. Attach a 9.5mm (3/8-inch) inside diameter hose on the radiator draincock (8115) to minimize loss of coolant when draining.

4. Open radiator draincock and permit coolant to drain into a clean container.

5. Remove drain plug on cylinder block (6010) to allow coolant to drain from engine, if necessary.

6. Dispose of old coolant properly. Promptly clean up any spilled coolant.


Filling

1. WARNING: USE CAUTION WHEN ADDING COOLANT MIXTURE TO RADIATOR TO AVOID HOT COOLANT OR STEAM BLOW OUT FROM THE RADIATOR.

Note: Use the following steps to remove air from the cooling system and to make sure fill is complete.

Note: When filling a crossflow radiator (8005), allow time for the coolant to flow through the radiator tubes to fill both tanks.

Close radiator draincock and install cylinder block drain plug.

2. Fill the cooling system with a 50/50 ethylene glycol and water mixture. Allow several minutes for trapped air to escape (bubble out) and for coolant mixture to flow through the radiator.

3. Install radiator cap to pressure relief position by installing radiator cap to fully installed position and then backing off to first stop. This will allow any air to escape, and minimize spillage.

4. Slide heater temperature and mode selection levers to maximum heat position.

5. Start engine and run at fast idle (approximately 2000 rpm) for three to four minutes. Shut engine off.

6. With engine off, wrap radiator cap with a thick cloth, carefully remove radiator cap and add coolant to bring coolant level up to filler neck seat.

7. Replace radiator cap to fully installed position. Then, back off to first stop. Operate engine at fast idle until the upper radiator hose (8260) is warm (water thermostat (8575) opens). To check radiator, shut engine off, wrap radiator cap with thick cloth and carefully remove radiator cap. Add coolant if necessary. Replace radiator cap to fully installed position.

8. Open the small cap on the top of the radiator coolant recovery reservoir. The large cap is for the windshield washer reservoir. NEVER put coolant mixture in windshield washer bottle.

9. Using a suitable suction gun, remove all coolant from radiator coolant recovery reservoir.

10. Add 1 liter (1.1 quarts) of 50/50 mixture of ethylene glycol and water to the radiator coolant recovery reservoir. Close the small cap.

 

Thanks for the info, the RABS info you e-mailed is very helpful.

I downloaded the Ford CD a couple of weeks ago, but I cannot seem to get the thing to work. The instructions for mounting the virtual drive, etc. seem a bit vague to me, but I really haven't had time to spend on it. If anyone would care to post clear, detailed instructions on how to convert the ISO file, and burn it to a CD, I would REALLY appreciate it. I work 6 days a week, and just don't have time to spend trying to figure this out. I got stumped trying to mount the virtual drive.

My temp never rises above where it normally runs when the gauge jumps around, just dips down and back up. So, it's not overheating, just to clarify.

Any thoughts on my ground strap question?

Oh, also my drain valve on the radiator is clogged, and will not drain at all.
Need new radiator, will pick one up soon.

Thanks so much for the replies, I also have a 91 Volkswagon Vanagon, and I'm a member of a VW Vanagon forum, but those guys are a bunch of smart asses, and it's hard to get clear answers from them. Here, it's much easier to get the info I need. I've got a 95 Windstar also, and the tranny just crapped out, about a month after I had a new engine installed, so that's the next big job.

Thanks
T

 

clean radiator core on fill neck side with long wire handle bottle brush or pipe brush, plumber's supply store, remove radiator, clean and flush out, remove drain valve and run small stainless stiff wire thru opening into tank, spray with hose nozzle or high pressure air to blow out crud, inspect with bright light, put valve back on with teflon plumber's tape to seal, tanks are plastic and not repairable.
i always drain mine by removing bottom hose, allows any big chunky junk to flush out.
some users have reported using liquid dish soap in coolant to clean system, probably 1/8 cup would be enough, run to hot and drain and multiple flush until all soap residue is gone, be sure not to overheat- would be easy to overheat with all the soap foam in cooling system, going to try myself next antifreeze change.

 

I had the exact same problem not so long ago, all it turned out to be was the radiator cap. The cap kept getting sediment buildup around it. I changed the cap and all has been well. (Original hoses upper/lower on a 94 4.0 w/180k). May want to pick up a new cap first and try that.

 

ground strap question, will it reach a non exhaust manifold bolt, on bell housing or intake manifold
exhaust manifold bolts and manifold subject to excessive rust and corrosion for a good positve high current ground

Winstar auto transmission failure after engine rebuilt, have auto tranny shop check for tranny input shaft/pump damage by engine reinstaller.