HoonTruck: Adventures in wrenching…

2015-03-06 17.10.28-2
Now that I have the truck in my garage, it’s time for me to get my hands dirty and turn some wrenches. I’ve picked my first test and for most of you it would be considered a simple one. I want to change the thermostat. This means draining the coolant, removing two bolts, and then popping the one thermostat in.
Sounds easy, right?
You clearly don’t know me very well…

2015-03-14 13.53.52-2
Now the actual act of changing the thermostat was easy. The bolts weren’t too hard to reach, the hose was pliable, and the old gasket/gunk between the housing and block came off easily. The previous owner was running without a thermostat, which gives me some pause, but I pressed on with the new unit regardless.
When it was time to fill the cooling system back up, I foolishly poured in about a gallon and a half of coolant (50/50 pre-mixed). That’s no quite enough, and I found this out after taking the truck for a quick spin. It came up to temp… and then went right past where I hoped it would stop.
I got the truck back into the garage and the overflow container was boiling. I could’ve cooked some seriously disgusting pasta in there in just a few minutes. I let the truck sit for a bit, and came back out a few hours later… after reading on the Internet that the truck takes closer to 4.5 gallons of coolant. Also, you’re supposed to let the system bleed/burp.
Got it.
The truck seems to run alright now with regards to holding temp, yet I’ve somehow managed to mess up the temp gauge that sits in the cab. It’s a mechanical gauge, and now it reads 230 degrees when the truck is cold (the thermo cap on the rad reads correctly at ambient temperature). The gauge will rise as the truck warms up, so at running temp it’s reading off the chart at the bottom of the gauge. The cap on the radiator shows the correct temp still. It seems I’ve cooked this gauge.
So a day or so later, I decide to take a spin in the truck and run over to a local brewery to fill up a growler. It all goes fine (minus that now shitty gauge), except for a new issue. I opened the hood to check on the temp when I got back to my garage… and saw this:
That’s fuel. It’s coming from the fuel pressure regulator, which is clearly not doing a great job of regulating said fuel. Oh well… something new to learn to fix. I’m still loving this truck, and I look forward to wrenching on it more and more.

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  1. nanoop Avatar

    I am very familiar with this nervous feeling before actually doing such a job…. You didn’t fock up big time, very good indeed, Gratulation!
    Don’t drive with leaking fuel, you’ll never know when exactly the dripping turns into a stream right onto something hot…

  2. mdharrell Avatar

    It’s not entirely clear from the earlier photos, but is that regulator there simply because a previous owner bypassed the mechanical fuel pump and added a high-pressure electric pump? As you’ve now discovered, that’s just more stuff that can break. My reactionary automotive grumpiness thanks you for this additional treasured bit of confirmation bias.

    1. neight428 Avatar

      Preach on! Complication is for race cars, the fundamentals fail regularly enough on old vehicles to keep them interesting. Keep your vacuum operated headlight doors off my hobby.

    2. 7FIAT's Later Avatar
      7FIAT’s Later

      I was wondering about why it has a fuel regulator also and came to the same conclusion. I have the stock mechanical one on my 390 and it pumps more than enough gas. So sometime in the past it probably needed a fuel pump and someone had a high-pressure one laying around and it was cheaper to buy a blocking plate and a cheapy regulator than a rebuilt mechanical pump. That kind of logic could mean other hidden problems with the hoontruck, but I hope not.

      1. mdharrell Avatar

        Even cheaper than a blanking plate, the photos of the engine compartment that Jeff posted earlier show a mechanical pump still in place, just bypassed (I think). It’s a little tricky to make out precisely where the fuel line is routed but that’s how it appears in some of the shots. My guess is a previous owner either thought a high-pressure setup was inherently cooler or was deeply concerned with the possibility of vapor lock.
        Personally I’d go with a mechanical pump, but even if Jeff prefers to stick with an electric unit there are low-pressure versions available that are more appropriate for carbureted applications. The latter is what I run in my racing SAAB now that it’s essentially impossible to get replacement diaphragms for its original mechanical pump, even though I’m really fond of the original: It has no mechanical linkage, as the diaphragm itself simply serves to transmit the fluctuations in pressure from the central part of the crankcase. All part of the joy of two-stroke design.

        1. Jeff Glucker Avatar
          Jeff Glucker

          So just forget the regulator and run straight from the pump into the carb?

          1. mdharrell Avatar

            Not if it’s a high-pressure pump, because then it’ll overcome the check valve in the carburetor’s float bowl, at which point fuel will pour out of the carb. If, on the other hand, it’s a low-pressure electric pump or the original mechanical pump, then you shouldn’t need the regulator.

  3. Kris_01 Avatar

    Sigh. When you change coolant, you drain the radiator and the engine block if there’s a draincock. Refill the system with mixed coolant. Leave the cap off, and start the engine. Turn the heater on full hot. Set the fan to low and the air direction to dash vent, and make sure the AC is off. Fill the rad as the vehicle is running until the rad is full, then let the engine run until the thermostat opens. Shut it down, fill the rad again and reinstall the cap. Should be purged of air now.
    Source: I’m a licensed mechanic.

    1. Sjalabais Avatar

      I googled that once and was ready to go. If memory serves me well, on a ’71 Volvo 145 you just take the thermostat out and put in a new one, without doing anything else. I remember it sitting more or less on top of the radiator…

  4. wunno sev Avatar
    wunno sev

    my most unfavorite job in any car is anything that involves coolant. fuck coolant. it’s nasty and sticky, it gets everywhere because it’s so easy to spill, you have to mix it or it costs twice as much, there’s a massive volume of it in the car, and even after you’ve buttoned everything up and got the car running, you can’t just toss it down the drain. the only worse fluid is brake fluid, and brake systems are usually designed such that the fluid stays contained and you never really have to touch it.

    1. smokyburnout Avatar

      Agreed, but gear oil also has to be up near the top. The smell!

      1. Frank T. Cat Avatar
        Frank T. Cat

        I have a feeling I’m one of the only people who doesn’t get bothered by the smell of gear oil. Probably due to my perpetual sinus infections cutting the strength.

      2. wrecksdart Avatar

        Certain gear oils are nasty, others kinda smell nice to me. Brake fluid and battery acid, on the other hand, both smell nasty and are horrible for any number of reasons. It never fails that I get little holes in my clothing every time I mess with batteries, and brake fluid should really be called mucus of the devil.

  5. Batshitbox Avatar

    I took my old ’70 F-250 from San Francisco down to Big Sur and back one time. On the return, just about to hit the SF line, it started running rough and losing power, but I nursed it home.
    Next day, pop the hood, start it up, and YEOW!! shut it back down! Fuel spraying directly on to the exhaust manifold. I can’t remember from where, but it was an easy fix. Easier than putting out an engine fire, anyway.

  6. Manxman Avatar

    Cool truck. Could be the temp sending unit and not the guage – had the same problem once.

    1. Jeff Glucker Avatar
      Jeff Glucker

      Yeah I think I’ll check that first

  7. Landon Cook Avatar
    Landon Cook

    There is a company that can rebuild that whole dash cluster to factory condition. It’s a bit pricey but well worth it if your looking to restore it.