I’m very fond of the Marshal, my 1989 Ford F-150, a generous gift from David, though it hasn’t really proven to be the trouble-free workhorse it really should be, and I think I have myself and the cruel realities of time and physics to blame for that. Sure, the inline-6 300 cubic inch/4.9-liter engine is the robust beast legends claim it is, but it’s all the crucial bits bolted to it I haven’t exactly had the best luck with.
On the way home from first getting the truck, it was the alternator that failed. I replaced that, then later it was the starter, which I also replaced, then some teeth on the flywheel broke and I ended up having to start it with a wrench for far too long (I need to return that wrench to David, btw) but then I finally replaced the flywheel and clutch and I thought all was finally great!
And then it overheated, suddenly and dramatically, as I returned from a day of taking the kid canoeing. Ugh. What did my truck to so horribly in a past life as a washing machine or industrial mixer to have to pay so dearly in this life? Anyway, I was dealing with this:
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This time, though, I thought I’d actually try and solve the problem instead of letting it just sit forlornly for months and months; I think this time I got to it in just, what, a month? Something like that. It’s progress!
My friend and colossal helper of misguided projects, Andy, once again offered his well-appointed shop and well-organized tools and considerable expertise to lend me a hand, so I babied the truck over to his shop and showed up with it geysering steam like what I imagine a red-hot meteorite landing in a Vegas casino fountain would be like. But, the truck made it, barely, and that’s what mattered.
It looked like the water pump was the culprit, as that seemed to be where the coolant was escaping, and there was also a loss of power steering, which seemed to be the result of drag from the bad water pump on the serpentine belt. You can see the offending water pump in the middle there, revealed by the removal of the fan and belt and hoses: 
I got a new water pump from Advance Auto, and it seemed to be a match for the old part. It fit in the old pump’s place just fine, once the hoses and bolts were laboriously worked off, but pretty soon we realized that something was, well, different.
The new part had some different dimensions for no good reason I could figure out. The casting was thinner around the bolt holes, which meant that the original bolts couldn’t hold it firmly to the block, because they were now too long, thanks to the thinner casting. We compensated for this with some nuts:
The bigger ass-pain was that the threaded bit that held the fan clutch in place had become, again for no good reason I can determine, smaller. By like, 5mm or so. Why? Why, why, why? What was gained here? Were both of these changes just to save a bit of metal? Was it just cruelty? What possible engineering advantage could have come about from this change?
In the end I had to buy a new fan clutch, too, because some engineer somewhere had to listen to some drip above them who decided that all the dimensions on this water pump needed to be changed just enough to make life harder and more expensive for some poor bastards who dared to try and replace the damn thing.
Finally, it did get replaced, and we also pulled the radiator and flushed it out, causing it to disgorge several clumps of an unpleasant brown muck that resembled, in size, shape, color, consistency and level of appetizing nothing so much as healthy human turds.
Some of the coolant looked like maybe there was oil in it, which is, of course, not good. I showed David the engine oil, though, and he seemed to think the engine was basically okay, so I’m just going to go with that until I get proven otherwise, likely on the side of the road in the rain somewhere.
The point is the truck runs again without creating more clouds than the break room of a vape store, and once again I’ve been reminded that wrenching on cars is always an ass-pain, somehow, somewhere.
Why did they change the sized of that damn water pump? Who stood to gain? Oh well.
Hey!
Cool!
Looking at Rockauto, your truck has the 1993 and newer water pump on it for some reason. Engine swap?
Every automotive casting I’ve designed has the part number cast in, so the 15th owner 40 years later can go order an exact replacement.
There won’t be any in stock, but that’s not my fault.
Look at everything hanging off the front of a good old straight six with all the room in the world to work on. I would buy a new clutch fan and dance.
I will vote the long era of the 4.9 inline six is the culprit. Possibly during a switch from SAE to Metric, or more probably a change in vendor for ford and a price delta based upon 3% material savings or something stupid like that. 10 cents per part does not mean much normally but over 10,000 or more of these motors per year and the savings is enough to pad some Industrial Engineer’s resume.
Possibly related but a lot of the parts I’m getting now that come with bolts that originally would be 13mm are now coming with 12mm…is this just shit aftermarket parts or what?
More likely the orginal’s were 1/4 inch and then instead of switching to 13 MM, they went to 12 to save a pittance.
We’ve got to stop describing metric bolts by the hex size.
13mm and 12mm hex metric screws will both have the same actual M8 thread, it’s just the 12mm one will be to the Japanese JIS spec because it’s lighter/less unlucky.
I didn’t own a 13mm spanner until I bought a British car.
I’m in the opposite position, I started with German stuff and 90s Fords, so I have extra 10mm and 13mm wrenches, and my 12mm and 14mm languished until I had to work o. a GM car. As an aside the 15mm gets a workout because it’s a common size on bicycles.
Mmm… bicycles…
Bicycle repair can be very satisfying.
Thank you for putting the capacity in litres!
Now if he could just spell litres correctly…
I would take an F-150 of your truck’s generation over pretty much anything that came after it. It’s from when trucks were trucks and cheaper than full-size sedans. Pickups have gotten so ridiculous these days. And yes. I am dating myself.