Need advice on radiator replacement

I easily removed the block drain plug from several of my Gen II Civics. Unlike their Detroit counterparts, the Honda plug is a machined bolt with gasket rather than a pipe (thread) plug.

I assume that Honda continues to use machined bolts in the later models.

JT

Grumpy AuContraire wrote in news:uOOdnb7LKNKJKZvQnZ2dnUVZ snipped-for-privacy@giganews.com:

All male screw-threads these days are rolled, not machined. This is true whether they're tapered pipe-threads or staight-threads.

Block-drain-plug sticking is due to two factors:

The 19mm-head ones are the ones prone to sticking. The ones at the /rear/ of the block are much smaller than that, and are a LOT easier to get loose.

i don't either. and it's academic given that you can't drain the cabin heater so that thing remains full of old coolant anyway. just change it now, then change it again in a few weeks - even if the antifreeze formulations are different, that'll take care of it.

use ready-diluted coolant or use distilled/de-ionized if you buy full strength. don't use tap water or softened water, not even to flush the engine.

you can't rely on the color as an indicator of whether it's long life or not. and besides, it's irrelevant if the shop used tap water as dilutant.

that may be true, but using tap water has a bigger negative impact than worrying about used antifreeze. besides, the heater matrix inside the car has both inlet and outlet at the top, so you will never drain that thing. so, while you are indeed correct that draining the block is the "right thing to do", it's also a pita and can be dispensed with if you can handle the expense of changing the coolant again in a couple of years.

but it's also a pita to access. personally, despite the fact that i'm super-anal about most car things, i just change the coolant a couple of times. it's no worse than the dilution effect that works for transmission fluid.

Just make sure that you have them in the same position or else the ATF hoses may not reach.

Accord , 24 mm I believe.

Clete wrote in news: snipped-for-privacy@4ax.com:

Not too sure about that. The Integra's 19mm bolt is torqued to 59 ft-lbs. The Accord's to 43 ft-lbs. That hints at a smaller bolt.

However, I think the '88-'91 Civic's drain bolt is the same size as the Integra, but is torqued only to 29 ft-lbs. What's going on? Thinner block?

OP might, in fact, have difficulty getting his block-drain loose unless he has the car off the ground high enough to be able to use a cheater bar.

In any case, my original statement was the result of me mixing up Toyota and Honda. Honda uses much larger drain bolts than Toyota. Sorry.

I am looking at the instructions for block heater install from Honda The 24mm is the block heater head size. The drain plug calls for a 8mm Allen socket to remove. Accord (L4)

My old relics have one in the front middle of the block. I'm sure that back then, (early 1980's), they were machined. Remember, I'm dealing with antiques!

JT

Just out of curiosity, I'm trying to understand how the coolant flow works. I assume the coolant has to flow into the radiator through the top hose, and back to the engine through the bottom hose. But the bottom hose is right at the thermostat housing, and I would have expected the thermostat to be in the engine's outflow path. The way it is, it seems that as soon as the thermostat heats up enough to begin to open, cold water would flow through from the lower hose and shut it off again. Could someone explain how it actually works?

if you have a garden hose, and you're interested in delivering water to your lawn, it doesn't matter where you have the faucet - it can be at one end of the hose or the other as far as water flow control is concerned. with the thermostat, same principle applies.

regarding control, a thermostat sitting at the hot end of an old-fashioned system doesn't allow flow until it's hot enough to open. there can therefore be both hot spots and cold spots in an engine because there's no through-flow. you can also have cycling between hot and cold as this stuff circulates when hot enough to open, then stops when cold enough to close, etc. this is an issue with fine-tuning engine mixture, and thus emissions control.

both these are solved by having a bypass system where there is always flow, and cooling is "added" by gradually diluting the stuff that's flowing with coolant at the temperature you want. the honda thermostat, and more specifically, the wax expansion bulb, sits in the bypass flow at all times, so its operation is controlled by that. and flow through the radiator is determined by the temperature of that bypass circuit. water coming into the circuit from the radiator only has the smallest of effect on the thermostat if at all, because the main flow the thermostat sees is actually coming sideways from the cylinder head.

Ok, that explains it. Thanks very much, Jim.

Ok, I got it done. And so far - no leaks. :-)

I'll need to check it later to make sure all the air is out. When the dealer did the 30k mile service, which included changing the coolant, they didn't get all the air out. I know that because the transmission wouldn't go into lockup mode at speed, and one of the experts in here said it was because the computer won't permit lockup mode unless the engine is fully warmed up, and the temp sensor used to decide that won't work correctly if it's in an air bubble. That turned out to be exactly correct, and after bleeding the air out, lockup worked fine. So that's my ultimate test for air in the system.

It took exactly one gallon of coolant, including new stuff in the overflow bottle. So there really is a good bit that doesn't drain out unless you drain the block, as Tegger said.

Aside from it just being difficult to get to things, the only real problem was getting the fans and hoses past the A/C hose. I tried to do that very carefully, and think it went ok. But I do understand why someone might prefer to jack up the car, remove the splash guard, take things off the bottom of the radiator, and then remove it. It might actually be easier that way overall.

One other small problem was making sure the rubber pads on the bottom went into the wells in the frame. If one side went in, the other side didn't want to. So I had to wrestle with that a bit, but finally got them both in.

Well, I appreciate everyone's help with this. I saved $260 doing it myself, and kinda enjoyed doing it. So thanks for all the advice.

One other question. If removing the block drain plug isn't feasible, would there be any way to siphon out the coolant remaining in the block? If you removed the upper hose and inserted plastic tubing, wouldn't it run into the water pump? If so, that would presumably be a no-go. And the lower hose would be blocked by the thermostat. That would leave only the place where the bleed valve screws in - if that's on the block side of the thermostat. Well, I was just curious if anyone had ever looked into that possibility.

you'd need a /lot/ of air in the system to cause that. and this is a frequently mis-diagnosed problem. yes, the coolant level can tell the computer not to lock up the torque converter, but it can also be caused by issues with the transmission selector switch - in my experience, that can be more common on hondas. if the problem recurs, re-post and i'll link you to a write-up of how to fix it.

like i said, you need to bend the hose a little - it's soft aluminum and can accommodate that kind of thing if not done regularly.

but you can't get the radiator out that way - that suggestion was, let's just say, "mistaken".

yes, you could use a siphon... [joke]

not unless you used a real thin tube and got real lucky. otherwise you're just going to poke it into the cylinder head cavity.

this is like people waiting for oil to drain for extended periods when doing their own oil changes thinking they're getting the last drop out, but not understanding that there's still a whole load of oil that'll never drain because it's in oil galleries, pumps, cam pools, etc. all that happens to that is dilution, not full change.

like oil, all you can reasonably do with your antifreeze, short of stripping the engine down and rebuilding, is either remove the drain plug, or just change the coolant again in a week or so. if you're doing the latter yourself, it's not expensive and the dilution of old fluid will be down to mere ounces, so it's simply not worth worrying about.

Peabody wrote in news:20101215-144031.120.0 @news.cox.net:

Used to be that way. But emissions laws demand more precision, so the thermotat had to be moved.

There's a bypass mechanism that prevents the thermostat from closing.

Plus, the system is a high-flow, low heat-transfer design, so once at operating temperature, the thermostat tends to stay open all the time.

Starting from the rad's upper tank, the coolant:

There are many more details, but this is the gist of it.

Peabody wrote in news:20101215-203224.560.0 @news.cox.net:

Well there y'go. I appear to have been overly pessimistic. Good work.

Peabody wrote in news:20101216-001312.310.0 @news.astraweb.com:

The water pump is at the back of the block, kitty-corner to the upper rad hose. You won't be able to reach it with tubing stuck into the upper hose outlet.

I suppose it might work, at least to a degree. Provided you managed to get the end of the siphon hose right to the bottom of the water jacket through the upper rad hose outlet, you'd be able to remove /most/ of the quart that's in the block.

But you'd still leave enough behind to compromise the new coolant and reduce the corrosion protection to the baseline 2-years, just as though you'd never tried that. Corrosion attacks the head-gasket first, and that's a very bad thing.

What you can do in lieu of pulling the block drain is to drain and fill the coolant as you just did, every two years. No need to remove the rad, just open the rad drain and let whatever wants to drain out, drain out (turn heater to full-hot first). That way most of the coolant will be fresh most of the time, and corrosion protection should be mostly OK.