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Discussion Starter #1
Every time I shut off my truck, within a few seconds it sounds like somone's perculating a pot of coffee in my glove box:crazy. This seems to be heater core related. I'm losing a very small amount of antifreeze somewhere and can't find it around the engine/radiator/hoses etc.

In the past with other vehicles when I had heater core leaks, I always had coolant residue on the pass. side windshield from running the defroster. I don't have this on my rig. Would anyone recommend removing/inspecting my heater core and has anyone else had this gurgling noise from the heating compartment on their vehicles?Other possible explanations would be appreciated.;)
 

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That sound is just indicating you have air in your cooling system. Find your self a local parts store that rents out tools and rent a cooling presure tester and put your system under the max presure your radiator cap indicats and look for leaks under your truck. Do'nt go over that presure or you can possibly blow a gasket or cause a leak somewhere that there wasnt before. Other option is find a shop that can presure test it for you and find the leak. Also you can check all the hose clamps and make sure they are all snug, if there was any engine bay work done since it started leaking.
 

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Discussion Starter #4
Thanks Ewgoetz and Mieski 5 for the input. One thing I neglected to include in my initial post is that I replaced the radiator cap with a higher pressure (16psi) instead of the factory 13. My thought was that I could "force the issue" to the point of being able to find the leak as I've been all over the engine bay and unable to detect the leak, leading me to the heater core which is obviously out of sight.

I'm also wondering if when I changed my water pump last year that maybe I didn't "burp" all of the air out of the system when I refilled the system and that the air is obviously trapped in the heater core area because of this. Makes perfect sense as that's probably the highest point in the system and air would tend to sit there.

I will go over the procedure that you sent me Mieski and see if I can get this thing to burp! Thanks again:thumbup
 

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That's good to know jowens, I never had to change the one in my previously owned '85 bronco, but the one's I've changed in the '77-'79 f-series with factory air are kind of a pain:banghead.

Due to the fact that I have air trapped in the heater core area, I may not have to worry about changing it yet. I noticed yesterday that after an extended driving period, I had some coolant in the reservoir (I run with a dry tank) which tells me it's overpressurizing and blowing it back in the plastic tank.
 

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I noticed yesterday that after an extended driving period, I had some coolant in the reservoir (I run with a dry tank) which tells me it's overpressurizing and blowing it back in the plastic tank.
yo,

My 96's platic side seams have leaked; mostly ovenight &/or during eng cool-down
I use baby powder; sprinkle usual suxpect areas and see if it shows the origin/ trail - tuff to do on running engine... I heat it up until norm op temp, then shut it down, clean off any wet spots and then sprinkle and start while fan isn't on

Replace t stat.

Pressure Tester is avail at AZ LOAN-A-TOOL® PROGRAM
& other parts store. It will test cap as well.

Check
coolant for contaminants such as rust or corrosion. Also, check for color discoloration
for coolant in
engine oil
in transmission oil
Is oil evident in coolant?

If engine oil is evident on vehicles with an engine oil cooler, REMOVE engine oil cooler and INSPECT for damage. REPLACE if damaged.
If engine oil is evident on vehicles without engine oil cooler or if oil cooler checks out OK, REMOVE cylinder head as outlined in Section 03-01A, Section 03-01B, Section 03-01C, or Section 03-01D, depending on engine, and INSPECT for leaking head gasket and head or block cracks.

If transmission oil is evident, check/replace transmission oil cooler in radiator as outlined in this section and check condition of transmission oil as outlined in this section.


Does engine overheat?
B3 CHECK FOR AIRFLOW OBSTRUCTION
Visually inspect A/C condenser core and radiator for obstructions, such as leaves or bugs.
B4 CHECK WATER THERMOSTAT OPERATION
Allow engine to run for 10 minutes.
Feel the inlet and outlet heater water hose and the underside of the upper radiator hose.
Are the upper radiator hose and heater water hoses cold?
Yes REPLACE water thermostat.

no LEAVE engine RUNNING. GO to B5.
B5 CHECK COOLING FAN
Check for proper cooling fan clutch operation. Perform Fan Clutch Test. Refer to Component Tests in this section (this is a Ford typical strobe light test; so just ck it visually.

Did cooling fan clutch operate OK?
Yes CHECK the following:
Rust or scale in radiator
Water pump shaft and impeller
Collapsed lower hose

no REPLACE fan clutch
 

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Discussion Starter #8
Thanks again Miesk5. I haven't even gotten her burped yet. I work 12 hr shifts @ a power plant and this is my night shift weekend so I'm planning to get to the bottom of this tommorow.

I replaced the t-stat when I replaced the water pump less about 1000 miles ago. I will however verify true coolant temperature since I recently purchased one of these http://www.summitracing.com/parts/MRG-2471B/. My guage well, you know, it's my guage:banghead, it goes to normal as soon as I turn the key on (just like my oil pressure is normal when the truck ain't even running and key on)!:histerica Read the threads on that too so I know not to trust anything on my instrument cluster til I can install some aftermarket guages.

Will post results.....
 

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Thanks again Miesk5. I haven't even gotten her burped yet. I work 12 hr shifts @ a power plant and this is my night shift weekend so I'm planning to get to the bottom of this tommorow.

I replaced the t-stat when I replaced the water pump less about 1000 miles ago. I will however verify true coolant temperature since I recently purchased one of these http://www.summitracing.com/parts/MRG-2471B/. My guage well, you know, it's my guage:banghead, it goes to normal as soon as I turn the key on (just like my oil pressure is normal when the truck ain't even running and key on)!:histerica Read the threads on that too so I know not to trust anything on my instrument cluster til I can install some aftermarket guages.

Will post results.....
yo,
yw,
Look in my site @ http://www.broncolinks.com/index.php?index=649 for the 96 Bronco coolant temperature gauge/sender test Link



Instrument Cluster Connector C1
Pin Number Circuit Circuit Function
1 904 (LG/R) Charge Indicator Lamp
2 932 (GY/W) High Beam Indicator Input
3 57 (BK) Ground
4 450 (DG/LG) Fasten Belt Indicator Input
5 29 (Y/W) Fuel Level Input (with Tachometer)
6 19 (LB/R) Instrument Cluster Illumination Input
7 57 (BK) Ground
8 2 (W/LB) Right Turn Input
9 648 (W/PK) Tachometer Input Signal
10 398 (BK/Y) Tachometer Ground (for 8 Cylinder)
11 784 (LB/BK) Low Range Indicator Input
12 210 (LB) 4x4 Indicator Input
13 640 (R/Y) Power Supply in RUN and START
14 16 (R/LG) Charge Indicator Input


see Image k20303c for Instrument Cluster Connector C2
Pin Number Circuit Circuit Function
1 875 (BK/LB) Unique Ground to Gauges
2 658 (PK/LG) "Check Engine Indicator" Input
3 603 (DG) Anti-lock Brake Warning Indicator Input
4 977 (P/W) Brake Warning Indicator Input
5 � Not Used
6 29 (Y/W) Fuel Level Input (Without Tachometer)
7 3 (LG/W) Left Turn Input
8 31 (W/R) Oil Pressure Input
9 875 (BK/LB) Unique Ground to Gauges
10 39 (R/W) Temperature Input
11 531 (DG/Y) Brake Level Switch Input
12 608 (BK/Y) Air Bag Indicator
13 640 (R/Y) Power to Gauges, Hot in START or RUN
14 � Not Used


and; Pull the R/W wire off sender; ground it; turn the key to Run. If needle pegs, replace the sender. If not, diagnose the circuit.


-- OIL PRESSURE;
Test & Overview in a 96 from 1996 F-150, F-250, F-350, Bronco, F-Super Duty Motorhome Chassis Workshop Manual: The oil pressure gauge is a magnetic movement design consisting of a bobbin/coil assembly, a return to zero magnet and a primary magnet. The shaft and pointer are connected to the primary magnet. The bobbin/coil assembly is pressed into a metal housing which has two holes for dial mounting. The gauge operates through a pressure activated switch. When the engine is started engine oil pressure closes the switch, providing a ground circuit for the gauge coil. Current flow through the gauge coil to ground causes the primary magnet and pointer to rotate, providing an oil pressure reading on the dial face. The oil pressure gauge does not require adjustment, calibration or maintenance. Also, never remove the pointer indicator from its shaft. The oil pressure switch controls the magnetic oil pressure gauge's pointer position. The oil pressure switch closes under normal engine operating conditions (oil pressure above 42 kPa [6 lb/sq in]). The oil pressure switch opens with the engine (6007) off and no oil pressure. Check gauge operation as follows: With the key in RUN and the engine off, disconnect wiring connector at the switch. The gauge should indicate on the LOW graduation or below. Connect the wiring connector to the engine block ground. The gauge should indicate just slightly above mid-scale. If the oil pressure gauge tests within calibration, replace oil pressure switch. If the gauge still tests out of calibration, replace oil pressure gauge.
Source: by Ford via miesk5 at FSB

more @ http://www.broncolinks.com/index.php?index=949
==

Other Gauges and Indicators @ http://www.broncolinks.com/index.php?index=429
 

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Discussion Starter #10
Update......

Was in the process of burping the system yesterday when I noticed a small amount of coolant puddled up in an area below and to the left of the t-stat housing. There's a small area on the timing cover that's kinda hard to see but I took a led flashlight to inspect everywhere I could think of to make sure I didn't have a leak.

Turns out I did and also found that it had a very small leak @ the t-stat housing where the L-shaped heater hose hooks onto it. Also discovered that I had a crackling noise coming from the water pump. This was very a loud and sharp noise that I verified was coming from the water pump with the ol heater hose to the ear test. This screamed pump cavitation to me as I deal with this kind of stuff all of the time @ work.Soooo, I got to thinkin.

Last year when I replaced the water pump, the parts guy said he had a new water pump and it was a high-flow pump. I didn't care if it was high-flow or not, just wanted a new, not rebuilt pump so I bought it. I think it was a "GMB" brand and I purchased it @ Advance Auto. I've been having ALOT of trouble w/parts from Advance and O'reilly's etc. and have been buying parts from the dealership and NAPA since getting my rig back on the road again in Sept.

Soooo.... Here's what I did: Pulled t-stat housing and t-stat. Noticed that the heater hose fitting (factory) didn't have a barb on the hose nipple and that the fitting was leaking. Then pulled water pump and didn't find any leaks, signs of bearing failure, but I did have a little axial movement in the impeller shaft. Went to NAPA and got new housing,pump,L-shaped hose and t-stat. Was pleased to see that the new housing not only had a hose barb, but also had the threaded plug for future aftermarket guage!

Wanted to compare the guts on the water pumps since one was supposed to be high-flow and the one from NAPA was not, so I took the plates off of both of them. They appeared to be the same by all accounts as I measured the impeller veins, suction, volute, and discharge area. The only difference is that the surface of the high-volume pump had a round plate tacked to the veins. As soon as I can I will try and take a pic. of this

Anyway, I installed parts, did the burp, and low n' behold, no more perculating behind the glove box! Took a while to get the air out, and one thing I might add, is that to speed the burping process up a little, I took a pair of needle nose vise grips and pinched down on the pass. side heater hose. Not all the way of course, but enough to restrict flow, get good suction flow and pressure, making it much faster to get the air out. Thanks again for all of your help fellas.

Now onto those gauges...... Oh by the way, my temp guage is now working appropriately.:thumbup Wish I could say the same for oil pressure guage:banghead
 
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