| Click to Post a New Message!
Page [ 1 ] | | |
|
|
|
Let s play Stump the mechanic
So here is the scenario...
1994 Ford V6 fuel injected gas engine.
Presently having 207,000 miles on it and runs GREAT!
No problems with fuel consumption, still delivers about 27-30 mpg on the highway.
No internal fluid leaks, ie: water in oil or vice versa
Recently decided to change t-stat, as I no longer had heat, and monitoring the temp gage, it (the needle) would wander up to "mid-normal" position, then moments later drop out, then slowly climb back up again. After its change, I still had the problems.
Then one horribly cold morning, I start the old girl up. As it is warming up, I notice a "wet" spot under the radiator. Long story short, I found that the topmost aluminum bracket had pulled away from the fins, causing a minor leak.
I drove the truck that day, watching the fluid level - no problem. The next day, after I arrived some 250 miles later, I decided to do some more checking. As I walk out of the garage, something catches my eye - the water pump let go, and I have fluid running everywhere.
OK I thought, time to start anew. I put in a new radiator, new water pump, new t-stat (again), new hoses, installed a flush kit. I purged the system and the vehicle runs great again, holding perfect fluid level and NO leaks.
.....But still no heat! (but at least the needle stays constant in the low range of normal)
Having the heater box open in the cab, I ran the engine until hot. I put my hand on the heater core, and she was blistering HOT ! EXCELLENT I thought. I turn on the blower, and within seconds, the heater was cooled off to the point, that no more heat was felt thru the core or the ducts. (!)
I took out my "zoo" gun, hooked it up to the heater hoses, and back flushed, forward flushed - you name it, I did it! (With the thinking that the heater was restricted, in some capacity)
Perfectly clear from the get-go. Hmmmm(?)
I removed the blower, with the idea that a "door" might be stuck open allowing cold outside fresh air into the blower plenum, causing the heater to "ice" over. Other than some tree debris, it was clear as well, and the door functions properly with the vacuum assist.
The vehicle runs great - no need to get rid of it, and yes I realize that spring is coming...eventually, and I won't need the heat, but....
I am stumped !
Anyone have any ideas?
- Willie H
|
|
 Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
Just a guess. Plugged heater core? A constant flow of heat requires heat energy in to roughly equal heat energy out. If the heat energy can't get in as fast as the fan removes it then you get cold air.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
kw -
Nope...not a plugged heater core. As mentioned, I used my zoo gun and it checked out fine.
(Incase you are unfamiliar with a "zoo" gun, it is an inline water valve, that has an air blast assist. It gets placed in the heater hose circuit, then as the fluid flows, one can hit the trigger for a blast of compressed air besides. It is made by Kalamazoo Industries, hence the name "zoo" gun)
I had thought the possibility of the core as well, however, in the troubleshooting attempts that I have made, I disconnected the two heater hoses and installed a pony pump into a bucket of water, with the zoo gun inline. The return line went into another empty bucket.
As I turned on the pony, I had a strong constant output from the core circulation, without rusty or any other type of contaminates. Perfectly clean and strong flow.
I then, just for the heck of it , gave it a shot from the zoo gun, with no difference on the output, as it was clear and high flow coming out.
- Willie H
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
Wow, you've done a lot of troubleshooting. Never heard of a zoo gun before. Could the core be partially restricted but still flow enough water to pass your tests? It might be interesting to use an IR thermometer (or night vision in the dark) while the heater is running and see if some areas of the core fins are significantly cooler than others. If the water into the core is hot it seems to me that it either has to be a core problem or an easier path for the water to bypass the core.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
I tracked down an issue similar to this, but on the A/C side. '92 K2500, new radiator/hoses/thermostat/sending unit/condensor/compressor cranking out tons of cold stuff - but after about 15 minutes it stopped coming outa the vents. Vacuum switches that control the air flow in/out of the common airbox dryrotted (204k miles). Replaced with new vacuum line between switch and airbox, problem solved.
//greg//
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
Hey Willy
I am having the Exact same problem with a 98 Cherokee. I have flushed the core out several times and have plenty of water coming out with the pressure of a Garden Hose.
My Temp gauge reads 195 degrees and I put in a New Thermostat just to be safe. I have inspected my Radiator and it is fine, I checked the doors they open and close as they should. I felt the upper hose going into the firewall side of the core and it is HOT the bottom hose is only warm. Before I dismantale the whole dashboard to replace the core on a 98 Cherokee, I wanted to be sure that was my problem and I am NOT sure. I have taken note that the Water Pump Housing looks pretty new as compared to the rest of the engine. My thought is that the fins of the fan are NOT turning, which allows water to pass thru it from convection and is enough to keep a straight 6 on cool but not enough to give adequate pressure to speed up the flow of how water to do as KT said in his reply, pass it thr to keep it HOT long enough. My next step when we have a day above 50 degrees is to take a hose off and run the engine to see if there is any pressure at all which should fill a bucket up pretty fast. I too, am stumped.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
I am also thinking a small vacuum leak. Is the heat valve vacuum controlled?
The cycling is typical of a vacuum leak. Air is sucked vacuum disappears heat is lost. Vacuum biulds until the material collapses and problem starts again. I had one similar, but could here the door opening and closing. It took for ever to determine where it was leaking. I think it was on one of the bellows.
In high vacuum work the moto is "Nature abhores a vacuum". A leak can take weeks to find.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
You say the heater core cools down quikely when the blower is turned on, sounds like the core is restricting the flow of coolant. flushing the core doesn't always fix the problem of having been plugged, forcing water through a couple of good passages can fool you to think that it flows good throughout, plus you already have it torn apart. unless you have a restriction somewhere else in the heater hoses, I'd say it is the core.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
Willie, we had a similar problem with a few of our Ford PSD pickups too.
It turns out Ford had a re-builder under contract here locally who had, let's say, a less than ideal QC program.
The re-man. water pumps were garbage, they had such a large tolerance that they couldn't develop any pressure to the flow, they barely exceeded the natural convection flow itself. As a result the small lines to the heater core saw barely any flow at all.
When we finally figured it out, because we replaced away from home and it worked like a champ, we raised heck with Ford here and they swapped us out our re-mans for brand new ones.
Best of luck.
|
|
Add Photo
Bookmarks: |
|
| |
|
Let s play Stump the mechanic
I had a problem a good 6 years ago and it turned out to be a leak in the vacuum system. Im particular, the switch had a bad plastic weld on it. Not sure if that's your problem, but it's worth checking out. I can't tell you how to check it out. But after as many miles as you have, some parts in the vacuum system may be a bit old and leaky.
|
|
Add Photo
Bookmarks: |
|
| |
|
Page [ 1 ] | | |
Thread 126269 Filter by Poster:
1 | 1 | 1 | 2 | 3 | 1 | 1 | 5 | 1 |
|
()
Picture of the Day
DennisCTB
Unanswered Questions
Active Subjects
Hot Topics
Featured Suppliers
|
Gas Generator Weather Protecti
03-18-2006, 08:46 
Digg It 
Del.icio.us 
