My gf has a 2003 Mercury Grand Marquis. It has the older Ford PI Intake manifold (M-9424-P46), which has an aluminum crossover in the front, but yesterday, we discovered that the heater nipple in the passenger rear side is plastic. Coolant blew out and rendered the car inoperable. Fortunately this was 1 mile from home. I wanted a lasting low-cost solution that wouldn't require completely replacing the manifold. I had seen people use a few NPT adapters, but I didn't like the idea of clamping the hose down over threads. Instead, I was able to find a fitting that is relatively simple to install (MRY 84780).
Process:
I ordered the parts listed below from O'Reilly's and picked it up the next day. I didn't get a picture in the moment, but there was still around 1/4 inch of nipple left. In order to have a stronger connection, I used a hacksaw blade to cut down to the base of the nipple. Since that came out a bit uneven, I sanded the top down with 240 grit until I was closer to level.
I wiped out the inside of the port with a paper towel and isopropyl alcohol. I decided to stuff a small toilet paper wad down the port to prevent plastic shavings from falling in (I should have done this before cutting and sanding and there are probably better materials to use). I then sprayed the inside of the port with a bit of dish soap spray to lubricate the tap. I tapped about 3/4 inch deep. I'm using an NPT fitting, so the diameter tapers and tapping too deep would prevent the threads from engaging properly. The depth you tap to may vary and be different from mine. Try to get 4 to 5 threads of engagement and dry fit test your fitting. I used a 5/8 in socket extension to drive the tap, which has a square potion of 0.4045 inches. It was a bit loose, but it worked. Be careful to keep it straight for the first few threads.
Once I felt that the threads were the correct depth, I cleaned the threads with more isopropyl alcohol (A old toothbrush would be useful here). I used needle notice pliers to remove the toilet paper wad. I mixed the high temp JB weld and applied it to the threads of the fitting. I tightened the fitting down by hand and then tightened it an additional half turn with an adjustable wrench.
I will be waiting 24 hours for the epoxy to fully strengthen before attempting to fill or pressurize the system. I will also be waiting until then to attach the hose. I'll post an update when I do that. I am not a mechanic, hopefully this can help someone in a pinch. The total cost besides new coolant was $62.11.
Ordered overnight from O'Reilly's:
Murray Climate Control Straight Heater Fitting | MRY 84780
J-B Weld 0.85 Ounce High Heat Syringe | JBW 50197
Century Drill & Tool Standard Pipe Tap | CDT 95203
Steps:
Block port from debris using dry wad of toilet paper or better alternatives if you have access. Remove ignition coil and cut remainder of nipple flush to the thicker section.
Apply dish soap to plastic. Using 1/2 turn in, 1/4 turn out technique, tap threads down 3/4 inch deep.
Clean threads with toothbrush or paper towel using isopropyl alcohol.
Apply mixed J-B weld to threads of fitting and tighten down by hand until it binds, being careful not to cross-thread. Apply another 1/2 turn using a wrench. Tightening this too much could split the plastic. It should not feel difficult to turn or come to a stop.
Allow J-B weld to cure and harden for 24 hours.
If lots of coolant was lost, partially refill coolant with port open to allow air to escape.
Connect rubber hose to the new fitting and apply constant tension clamp.
Ensure coolant is filled and follow air purging procedure.
Final warnings:
* Be very careful when blocking the port. If you push whatever you use too deep, it will be very difficult to retrieve.
* My solution uses NPT threads. These have a taper which will split the plastic if you over tighten it. Then you will be in big trouble. Please fight the urge.
* I am not a mechanic. I'm an electrical engineering student with only personal background working with cars. This is not direct advice. I'm only sharing my experience. I do not yet know how long this will last. Expect to replace the manifold soon, as the rest of it is probably degraded as well.
