Coolant change

cruizer101

The thermostat on my car, 97 Honda Civic 1.4, is gone (at least I'm pretty sure its the thermostat as the engine isn't heating up) and needs replacing, so I was planning on replacing the coolant also as I'm not sure when it was last changed and I think had to be drained anyway.

I've a few questions as I've seen slightly different methods.

In the haynes manual it says to drain from radiator then remove lower hose to drain the block, then to flush with tap water by putting hose in top of radiator.

Elsewhere, http://www.civicforums.com/forums/36-mechanical-problems-vehicle-issues-fix-forum/302900-timing-belt-diy-2-a.html#post4271491 post #3 about half way down page, it says to drain from radiator then from block with a different bolt, then to fill with distilled water run the engine, then drain and refill, warns not to use tap water.

So which do you think is the better option, I'm leaning away from the bolt on engine block as it seems like a bit more hassle then the lower hose.

But for the other stuff what is the better option, flush with tap water or run with distilled, also I know you can buy deionised from motor factors will this do same job as distilled.

Finally, coolant choice, was planning going with OAT non silicate as I've read that Honda use this kind (this mainly applied to US but I imagine its the same here). And coolant disposal, I know its pretty toxic so can I bring this to recycling centre to dispose of, I 'm pretty sure they take engine oil so hoping they take this.

Any other general advice on changing coolant is welcome.

daveharnett

cruizer101 wrote: »

In the haynes manual it says to drain from radiator then remove lower hose to drain the block, then to flush with tap water by putting hose in top of radiator.

Elsewhere, http://www.civicforums.com/forums/36-mechanical-problems-vehicle-issues-fix-forum/302900-timing-belt-diy-2-a.html#post4271491 post #3 about half way down page, it says to drain from radiator then from block with a different bolt, then to fill with distilled water run the engine, then drain and refill, warns not to use tap water.

So which do you think is the better option, I'm leaning away from the bolt on engine block as it seems like a bit more hassle then the lower hose.

I'd take more notice of the enthusiast forums to be honest. Haynes use an awful lot of cut and paste for general tasks like changing coolant. That said, if the hose is the easier option, I wouldn't lose any sleep over it.

cruizer101 wrote: »

But for the other stuff what is the better option, flush with tap water or run with distilled, also I know you can buy deionised from motor factors will this do same job as distilled.

If time permits do both, starting with the hose through the rad. A stream of tap water will remove more crap from the rad, but will do nothing for the engine side of the loop.

Slidey

Without knowing the specific engine, this is a general guide to changing coolant.

Heater switch to hot.

Take off bottom rad hose or remove bung from the bottom of the rad if it has one. Open rad cap. When it had all stopped coming out replace hose.

Are you going to change the 'stat yourself?

If you haven't been having any over heating issues I wouldn't be too bothered with flushing it. If you still want to, just use tap water, you are going to be re-draining it anyway and it will do no harm. I have been filling radiators for 11 years with tap water and never had a problem. Don't be tempted to use rad flush treatment unless you really need to.

JHMEG

You will probably have a bit of trouble getting the hose off the thermostat: use boiling water on the hose to soften it if you do. You might also have trouble getting the thermostat off but a sharp tap with a hammer will break the bond.

once you use anti freeze it doesnt really matter what water goes in, deionised water wont have any calcium carbonate in it so it wont cause any scale, also no salts so some folk reckon its less corrosive, it can be very corrosive though. The water from a tumble dryer is ideal for mixing with coolant for rads. As above, heater to hot, allow system to heat up, turn off and drain carefully. No need to flush unless it has debris or sludge in it, check for air locks after the refill.

cruizer101

daveharnett wrote: »

If time permits do both, starting with the hose through the rad. A stream of tap water will remove more crap from the rad, but will do nothing for the engine side of the loop.

Forgot to say it said to remove thermostat and leave heating on full in order to clear out the engine and heater matrix, because my 'stat is stuck open should be ok.

I've been thinking about it a bit more and think the fact my thermostat is stuck open might make it easier. I'll have to look at the coolant circuit a bit more but I think with it open I'll be able to drain all of the coolant just via the bung on the bottom of radiator no need to detach hoses and that. Then fill with water run for a minute or two to clean a bit. Replace the thermostat and then fill up with coolant.

Thanks for the tips, I'll let you know how it goes.

Also I know not having my engine heat up properly drops my mpg a bit, but does it do any other damage so long as I'm keeping revs pretty low as not sure how soon I'll be able to do this. Motor factors hadn't any thermostat weekend just gone.

cruizer101

Just to update on this, I did the job over the weekend.

Was easy enough to do, thanks for the tips, hot water definilty helped hose come off. In all the job took me about 2 hrs but could have been a fair bit quicker. Its just when not to experienced you are always taking slowly and double checking. If I had to do again I'd say I'd do it in an hour.

I'll just have to keep an eye out for leaks and on the coolant level in case any airlocks come out or that.