Assuming all the coolant hoses, tstat and water pump and radiator are already checked, any hidden coolant leaks in the middle after oil pan but before tranny has to be from the 2 freeze plugs, the rearest. Your truck should have 10 freeze plugs in total, 3 on left, 3 on right, 2 on front and 2 on rear. Most common leaks are from the right. There is no o-ring/washer on any freeze plug, just press in with or without water pump gasket maker.
For minor leak just use BlueDevil and forget replacing the freeze plugs. Be sure to follow manufacturer instruction, on top of that, do a engine cooling system flush again when the leak is gone (even if it's not mentioned in instructions), so that any leftover crystal or gunk formed by chemical solution can be flushed out as much as possible, if not they can clog your system and create more harm than good.

 

Heiko.... Thank you for the detailed reply which pretty well covers my problem and my questions, mainly the count of the Freeze Out Plugs and their location. It is most appreciated, thank you again.

I haven't removed the water pump as of yet. I did replace it about 20 years ago due to it leaking and was wondering if the rear portion of it had failed again, causing water to drain into the top of the engine underneath the intake manifold, then back and down the rear portion of the engine to where I see it dripping off the oil pan?..... Is that possible? I left the water pump on just so I could fill the block with water in an attempt to pin point this leak but will be removing it today.

Question for today: I have no knowledge of the "Blue Devil" item you recommend I use, but assume that it is an equivalent to "Bars Leak" that I have used in my youth quite a few times while working with my dad who owned a salvage yard in southern NJ, selling used cars occasionally that had cracked blocks due to the freezing Winter weather there. I will be doing a "Search" for the Blue Devil substance today. The question... Do you consider the Blue Devil to be superior to Bars Leak or about the same quality?

You may have picked up that I am now 92 years of age but still of sound mind and body... driving, working, etc, etc. However, occasionally my typing does suffer somewhat. My apologies when that takes place.

 

Joe, If your typing is all that suffers, you are in great shape !

Please stop talking yourself into "Old Age" ! Some guys are old at 50 and you are not ready for the ole rocking chair yet.

Can I ask where in SO. Jersey you grew up ? Pretty familiar with that area..

 

Many thanks for those kind words Hanky, I really do appreciate them. I mention the age thing from time to time so as to remind me to thank the Almighty for the positive reply to my request to linger on. I was just about to go out to do the final disassembly of removing that water pump to get a good look at the top back portion of it... a curiosity thing really as I'll be replacing it anyway.

I cleaned my fan-blade assembly up, then spray painted it gloss black... looks very nice if I do say so myself! Now I gotta clean up the entire engine compartment to match??

I'm from a little section of the World Hanky, called the Tri-City area of South Jersey... Millville, Vineland, Bridgeton, with me being born and raised in Millville which is directly west of Atlantic City by about 40 miles. I used to go back to visit family, relatives, friends once a year, and with four sisters, the original family, the spinoff families, relatives, etc etc.... would have made up a small army. However, as the many years passed... I have outlived them all... sometimes I wonder who was the lucky one(s)?

However, I'm very happy to be here, hoping there's a purpose to it all... Somebody's gotta fix this truck! 😎

 

I believe we have the right man on the job.

If I remember correctly there was a special long bolt that used to snap off when I attempted to replace water pumps.. It has been a while , but that bolt had a threaded stud on the out side end, maybe for alt bracket. Be careful with that bolt.
I had to drill a small hole in the center of the part stuck in the block then use a left handed drill bit that made removal a lot easier. Hope you don't meet up with that situation.

Worked that area of So. Jersey many moons ago, not far from Collingswood. Nice area .

 

Since you said the water pump is not thoroughly checked, so check the instruction below.

 

Heiko... It just dawned on me that the vehicle I installed a new water pump on some 20 years ago was my late wifes 1989 Crown Victoria... NOT this 1988 Ford F150. This dawned on me when I found that the AC Compressor and the Power Steering Pump retaining bracket was over top of a portion of the water pump (sigh). I've got a good excuse... guess what it is!

So, bottom line is that this water pump is is a good 36 years old! My Haynes manual that I bought in 1988 has swelled with humidity to where it is about 1-1/2" thick now, but still going strong. It says to remove the retaining bolts of the AC Compressor and the Power Steering Pump... HA!, the P/S/ bolts are in back of the pulley. Why did I ever loan my puller to my neighbor who was in the process of moving? New puller will be in Saturday (5th). No Idea where the retaining bolts are for that bracket. Ford actually designed a heavy duty holding bracket to go "Over Top" of the water pump??? Does it get worse or better? I'm so glad I'm doing this myself.

 

Hanky,
I appreciate the advice Hanky. I've been very cautious about working ion this thing as you might guess... yes, a broken stud would be the very last thing I'd want to run into. Actually most of the bolts seem to be slightly loose to me. As per my reply to Heiko... I kept thinking it was this truck I changed the water pump on some 20 years ago. In coming across the AC Compressor and P/S Pump interfering with the water pump removal, rattling my brain to suddenly realize.... The AC Compressor and the P/S Pump are on the wrong side!!! AAaaaGggHhh!! It was my wife's 89 Crown Victoria, same engine (302), but the accessories are reversed! The world is so lucky that I'm a patient man... people have gone quite mad and violent with less than this! I bought a case of beer just the other day.....................

 

Only one case ?

What are you going to do when the one case dries up and the job isn't finished?
All in fun, just be careful and take your time. In all that heat it is easy to overwork,lol.

We all know that keeping busy and continued learning is what keep us going.

 

If it's too much work to get to the water pump for inspection only, and when you get to it you are probably going to replace it with a brand new one along with your tstat. Maybe it's better to just inspect the 2 freeze plugs on the rear using a endoscope (snake camera) without dropping the tranny. Buy it on Amazon and keep it if you like it, it's inexpensive anyway. Just another option that might save you time and money.