Speaking of coolant, I can't find the engine block drain plug on my 1994 KA24E pickup engine. The manual show a bolt in a mysterious diagram with circles and squares labeled "left side of engine block", with no reference point. Help! The radiator holds 2.5 gal and I'm draining less than 1 gal out of it from the radiator plug.

Can anyone direct me to my drain plug? Thanks!

I really have never pulled that plug when doing a coolant change. Open the radiator drain c*** and make sure the dash heater is set to hot that way the heater core is open to flushing. I have never pulled the block plug.

You can't say c***? Anyway, yes the heater is full on and the drain c*** was pulled. Less than 1 gal drained.

Does that make sense?

That's about right. You can pull a heater core hose off the fire wall and back flush through that until only water comes out of the radiator drain. I can say c*** but I'd get in trouble for bypassing the swear filter. :p

That would mean I'd have to find a heater core hose? H*** I can't find the d*** drain plug.

So my concern (other than censorship of perfectly good automotive words) was that if I try to flush it (can I say that?) with water, I'm diluting what's left in there now (more than half the capacity). If I do this a few time times and drain only 1 only gallon each time I end up with 1.5 gallons of a very dilute mix of coolant stuck in the system. Then if I fill with a 50/50 mix I end up with something that's a lot less than 50% coolant. If I add 100% coolant I don't really know what the concentration is except that it's probably less than 50% (1.5 gal of water + 1 gal of coolant).

This just doesn't sound very scientific. Is it normal?? I guess I have to use 100% coolant for the last fill and ballpark the final concentration unless I can get all of the liquid out of the system after the last flush . . . Now I'm curious - is there no way to get all of the liquid out of the cooling system?

Generally draining from the radiator gets most of the coolant out. At the age these trucks are at I wouldn't risk trying to remove the block plug unless I was sure it wasn't going to break off, rust has its ways. The heater code hoses are located on the firewall behind the air cleaner. You will see two rubber hoses attached to the firewall. Remove one of those to back flush. You are not really diluting what is in the system if you back flush, once the system drains clear then you can stop back flushing. Just let it drain till it stops on its own. Next buy a gallon of green coolant and a gallon of distilled water. Mix those together in another container, this way you know you have a 50/50 mix.

I apppreciate the help . . . but unless the factory specs are wrong, the system holds almost 2.5 gal of coolant mix. Maybe I'm confused about what backflushing does, but assuming I will not be able to drain all of the water, won't there still be 1.5 gal of water in the system since I can only drain 1 gal via the radiator plug? Won't 1.5 gal of water stay in the system when I do the final drain from the radiator? Meaning there will be 1.5 gal of pure water in there. Which will dilute a 50/50 mix to something more like 20% coolant (1 gal 50/50 mix + 1.5 gal pure water). Even if I refill with 100% coolant it will make the final mix in the system only 40% coolant (1 gal coolant + 1.5 gal pure water).

If I'm wrong, what am I missing here? If backflushing removes all of the coolant and water in the system so there's nothing left in the system, then I get what you're saying and I should have to add about 2.5 gal to refill . . . If not, I just don't get it - the concentration will be wrong no matter what I do if the spec is right.

If you really want to be sure then remove the lower radiator hose, that should clear the block.

Rev_D21 wrote:If you really want to be sure then remove the lower radiator hose, that should clear the block.

I did that after I only got 1 gal. out from the drain c***. Just a little dribble came out of the hose, not even an ounce.

Waitaminute, you mean remove the lower rad hose from the rad or from the engine? I disconnected from the rad.

Well gotta get to work tomorrow so I gave up on any kind of system flush and just refilled and it took exactly 1 gal 50/50. I'll try again sometime if I can get more information.

Isn't it kind of hard to believe that there's only 1 gal in the whole cooling system?

Per the FSM, your KA24DE 4WD engine takes 2.37 gallons of coolant, including the overflow reservoir.

I believe removing the lower radiator hose from the engine side will drain the block, which would get most of the remainder of the coolant out from the block.

Yes, 2.375 gallons to be exact. You've said the only thing I haven't tried - removing the lower radiator hose from where it connects to the engine. I did remove it from the radiator and almost nothing came out. But frankly I don't see why it would make a difference where I disconnect it - the hose runs completely downhill from the engine to the radiator. I'll try it next weekend but if 1.375 gallons of coolant comes pouring out of the engine at that point it's gonna be messy!

I typically just drain and refill the radiator repeatedly... a case of distilled water is cheap, and those block plugs are a pain to get out. There have also been reports of stress cracks in the blocks of various engines at the block drains - so I'm not risking stressing them. Oh yeah... c***.

Heath

Q451990 wrote:I typically just drain and refill the radiator repeatedly... a case of distilled water is cheap, and those block plugs are a pain to get out. There have also been reports of stress cracks in the blocks of various engines at the block drains - so I'm not risking stressing them. Oh yeah... c***.

Heath

That makes perfect sense and I'll stay away from the block drain. But you're still left with water (1.4 gal if you believe the owner's manual) in the system after your final drain from the radiator . . . you can't get it all out . . . how do you make sure you have the concentration of coolant that you want (50/50) when you fill it up again?

So I guess nobody but me worries about the final concentration of the coolant mix?

Can you try parking the vehicle with the nose downhill? That should help drain it.
Yes, removing the lower radiator hose from the radiator should be the same as from the block, and hell, even the drain plug on the radiator itself should work. I'd pull the radiator plug at the bottom and massage the hoses with the vehicle's nose pointing downhill.

We don't have many hills in Florida - maybe I should drive to Georgia! But seriously, I'll give that a try.

BTW, I'm still hanging on this. Assuming downhill/uphill doesn't resolve the problem, is there any way to blow or suck the remaining water out of the system after it's been flushed so it can be refilled with the right mix?

Yes, both the rad plug and the lower radiator hose were pulled and produced less than a gallon.

To answer your question from above, maintaining a strict 50/50 ratio is by no means critical.

Being in Florida, you can probably run a much lower concentration. The more water that's in there, the better your coolant will cool. I run about 25-30% coolant in my Miata.

Oh hey you're in Florida too! Where specifically? I'm about 30 minutes north of West Palm Beach.

I'd guess to get a correct 50/50 concentration, you can keep draining & filling with distilled water until it drains clear, then fill the radiator to half the total system capacity with straight coolant. Then top off with pre-mixed 50/50 as required.

Papasmurf2k3 wrote: I run about 25-30% coolant in my Miata.

You must be able to drain it all to know what the final concentration in your Miata is? Or are you doing the math?

[quote="Towncivilian"]Oh hey you're in Florida too! Where specifically? I'm about 30 minutes north of West Palm Beach.

I'm about 30 minutes west of WPB. Small world!

I completely rebuilt my engine so yeah, it was completely empty.

I also bought 50/50 mix and then cut it with water by pouring it into another container, so that 50/50 mix was then (50/50)/50, netting 25.

I then had some older ~50/50 laying around that I used to just top off after a few days of running. It took about 1 reservoir full of that... so yeah, 25-30%.

Its not really an exact science.

On my Q, the radiator holds pretty much exactly 40% of the overall cooling system capicity, so I just use a case of distilled water for multiple flushes, then the last refill is with undiluted coolant, giving me a 60/40 water/coolant ratio. You will get a feel for how much coolant your radiator holds vs. the rest of the system when you drain and fill it and can adjust accordingly.

Heath

Coolant drainplug is located on the drivers side. Underneath the small EGR exhaust tube, and in between the dipstick and the firewall.

Here is a short video showing where it is:



Tools needed:

1. 1-inch 14mm socket
2. 8-inch flex head ratchet, or regular ratchet which will require #3 on this list .
3. 6-inch extension
4. 2-inch ‘90 universal joint adapter

You wont need the extension when going at it from below.

Below are steps that from another D21 owner wrote up:

Steps:

1. Hang a light off the brake line for max visibility. You’ll be able to see the bolt if you lean far enough back…..see video above for the “sweeping in” view.
2. Put the ratchet setup UNDERNEATH the small EGR exhaust tube, and in between the dipstick and the firewall, and you’ll literally be able to snag the top of the bolt easily sliding the socket up and down against the block until it catches and attaches smoothly. Once you feel it catching you can probably lean back/adjust light if needed and see it directly to help attach if necessary. It should attach very cleanly and flush to the block with no risk of stripping and lots of room to maneuver.
3. Once attached, if it’s the first time removing it (I had to remove it 6-7 times flushing the radiator before it was clean), you can swing the ratchet up from the position in the first picture below; and you’ll have tons of room to attach something as a breaker bar (I used an extension and deep-well socket).
4. Once you remove it the first time, there’s no need to add thread sealant per the FSM or even tighten it back down past snug to keep flushing the system, as I never leaked a drop doing it that way while the engine ran for 20 minutes each time. I would add the thread sealant when putting it back in for the final coolant fill though.

Here is a longer video showing how-ish i did it the first time: