October 2018 - Cooling system
I spent the majority of last month stressing about the car’s cooling system. Here’s a little read for you guys..
I randomly decided to check on my fluids one day and noticed some rust particles floating around in the radiator, I'm guessing one of the previous owners used tap water instead of coolant. I disconnected the two heater core hoses and out comes some brown, nasty, rusty looking water :( I start stressing about the amount of rust particles / gunk that is floating around the coolant system. I fitted a hose joiner to the two heater core hoses together and bypass the heater core temporarily as I didn’t want the heater core to clog and leak in the cabin. I guess I could have just removed one of the hoses and looped the existing one, but I didn't want to kink the lines. If you want to join the two hoses, this is what I used.
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I start researching how to get rid of the rust and came across an American product called Evaporust Thermocure (https://evapo-rust.com/thermocure), a non-toxic, non-corrosive, and eco-friendly rust converter. Safe to pour on your plants after you're done with it.. however, costs $60USD/Litre delivered to Australia :fp: There were cheaper alternatives available locally for $10-$15 but they are all corrosive, acidic or harmful to engine seals and gaskets, so I figured I'd just be safe and just pay the price of the Thermocure. The instructions were pretty simple, flush out your existing coolant as much as possible, pour the Evaporust into your radiator and fill with distilled water, run the engine for a few hours, flush the Thermocure out, refill with coolant and that's it. It's safe to leave in your car for a few days as well if you dont drive it much, which is what I ended up doing. I figured I'd clean the existing system out of all it's gunk first, and then change out all the coolant hoses, radiator and NB aluminium heater core when I do the timing belt service.
Fast forward to 3 days later, I decide to flush the Thermocure out of my car. I pack all my tools, and make my way to a mates place to work on the car. I hit the highway and 5 minutes in, I notice a little steam coming out of my hood. As I'm trying to assess the situation, I notice the water temp guage is sitting higher than usual, about 2/3rds of the way to full and climbing. By the time I find a safe spot to pull over, the needle is pointing to the maximum temp on the guage :( I switch the engine off, let the car cool down, and tried to figure out which hose had popped off. Whilst I've got my head stuck under the hood, the emergency highway patrol unit stops by and offers a helping hand. Just by sheer luck, they were attending to another break down a few hundred meters down the road, and happened to see my car on the side of the road. The patrol guy starts pouring water into my radiator, and I notice steam coming out the back of the motor. Of course, my mind jumps straight to the worst possible conclusion of a warped head or leaking head gasket haha, but as he continues to pour more water in, I notice the steam coming out of a split heater core hose.. the same hose I had looped the other day with the adaptor when I bypassed the heater core. I must have kinked the hose or something? But it split at the end where coolant flows back into the head, not where the adaptor was fitted. I got to work replacing the hose (luckily I had a spare hose in the boot), topped the system up with water, expressed my gratitude and off I went :lol: I'll have to do a compression test soon to make sure everything is fine, wouldn't want to do a timing belt service on a shot motor
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Having been through that little hiccup, I decided I wasn’t going to take any second chances with another coolant leak / overheating issue. I decided to do a complete overhaul of the cooling system, a new radiator, OEM water passages in case the existing ones have corroded, upgrade to the NB aluminium heater core, new thermostat and etc. I spent the next few days searching and ordering parts, including a used NB heater box for $50 - I thought this was a bargain, but it arrives damaged. The heater core box is cracked in multiple places as it was inadequately packed. At the same time, if some due care was taken during handling/delivery, it would have been okay with it's current packaging. Regardless, even if the heater box arrived undamaged, I wasn't really happy with it. Over time, the seals on it had worn down, all the foam on the inside had deteriorated and turned mouldy, I guess it's just wear and tear from the last 20+ years of use. I dont think its fair to ask for a refund from the seller as I am partly to blame for not asking for clearer pictures of the heater box, I should have known that the foam bits would be old and worn.
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I decide to make do with what I've got, so I stripped the aluminium core from the damaged housing, and I'll just swap out my copper core for it, reusing my NA heater core housing. A few mins with a pair of pliers and a screw driver and out it came.
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Here are the rest of the parts that will be going in my car during the cooling system overhaul.
Koyo 36mm core Hyper V radiator. This will replace the no name aluminium 44mm radiator that’s currently on the car. I chose the 36mm because I didn’t want to run a thick radiator, trying to minimise any additional weight gain. Thinner radiator + less coolant.. every bit counts!
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Ordered a Maruha stainless steel radiator pipe as the OEM one tends to rust out, OEM radiator hoses and bypass hoses, heater core hoses + grommets - one of the heater core hoses was used to when I got stranded on the highway.
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Maruha 78deg c thermostat, some hose clamps, OEM gaskets, coolant passage ways (thermostat top housing still in the mail), and an OEM thermoswitch
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And probably the most exciting piece I've found on yahoo (besides some green Mazda speed sway bars I found for Stephen), a brand new NB Heater core unit on yahoo japan. Perfect timing with this one, it showed up on yahoo the day the used/broken one arrived! It might not be anything exciting for you guys, but this meant that I could complete entire coolant overhaul with all new items, no more used parts! Everything will be brand new, and hopefully last another 20 years. It wasn’t cheap though, ended up at about $365 USD landed lol
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I also picked up a blower box refresh kit from Maruha
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Since the dash is coming out, the thought of deleting AC has crossed my mind. Apparently, I will have to degas the system of refrigerant to remove the AirCon box, before the heater box can come out. My old EK K20A had no PS or AC, and it definitely wasn’t fun driving around drenched in sweat.. but my silly, inner street-racer wants to delete it (the amount of weight removed won't even change the power to weight ratio by that much lol).
I haven't decided yet, so I bought the OEM HVAC control unit anyway, just in case I ever decide to remove it. I didn’t have to buy this to delete AC from the car, I could just leave everything as is, or just buy a control knob from a Non AC car, but my OCD got the better of me. The Non-AC fan control knob is discontinued, and so are the three sliding adjusting knobs, so I guess it’s another reason to have a brand new spare unit lying around.
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Along with the HVAC control unit, I also picked up an AC delete kit, with firewall grommets as well. There’s also a shorter bolt that’s on its way, for when the AC bracket is removed and a replacement shorter bolt is required to seal the oil pump housing back in place.
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I’m sure that takes care of all the HVAC components, let me know if I’ve missed anything!
I've seen the way you drive, you've got a heavy foot!!
Since I’ll be pulling the dash out, it's also the perfect opportunity to upgrade to the NB brake/accelerator pedal assembly. If you’ve got a heavy foot, the NA assembly is prone to splitting/snapping just like the image below (crack seen just above the return spring for the accelerator pedal).
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An upgrade to the NB assembly is ideal as the metal is thicker than the NA assembly. You could weld some reinforcement plates on the back of your NA assembly, but this is just easier. There are some things I’m willing to pay a pretty penny for, but $250 USD for a brand new OEM NB brake pedal assembly isn’t one of them, so a used one it is.
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Of course, I didn’t want to install it in its current condition, so I got to work with refreshing it. I unassembled the unit, and soaked it in some vinegar overnight to remove the surface rust. A light rub with a dishwashing scourer removed it all, cheap and easy!
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I headed down to a mates workshop and gave it a quick sand, a few coats of primer and finished off with some satin black paint. After it dried, I reassembled the unit using all the old hardware, just to see what it looks like (I did order some new bolts and washers and etc, just waiting for them to arrive).
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It turned out quite well I think? I would have preferred to zinc coat it, but it wasn’t worth sending away just to coat one item.
Before
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After
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I can’t wait to rip the dash out now! It will probably be the next post. I need to swap out all the under dash components before the car heads into the workshop for its timing belt service. Im still about 10,000km shy of the 100k kms milestone, but the car is 25 years old, so better to do it now before something else breaks!