1986 honda prelude 1.8 dual carb

where are the freeze plugs located and how do you know if one is bad?

 

It would be hard to describe the location of each, but knowing if one is bad
isn't hard.

First, the only reason I've ever seen one go bad is by corrosion from using
tap water in the cooling system. That is bad news because it causes
widespread corrosion. If you remove the radiator cap (engine cold) and run
your finger around the inside of the radiator neck there your fingertip
should come out with no trace of rust. No rust = probably not freeze plug
trouble.

As for the freeze plugs - when one fails, a hole will have corroded through
it, usually at the edge. Sometimes it will produce only a drip, but more
often it is anywhere from a trickle to a flood of coolant. Once you see the
coolant leaking, it's time to get a flashlight and stick your face into the
greasy areas to follow the coolant back to the source. With a little bit of
luck you will find it is actually coming from an end of a hose.

Replacing freeze plugs is a real headache. It's easy once you get enough
room to swing a mallet, but very often that means removing the engine. Don't
even think of using stop-leak products to try to patch a leaking freeze
plug - not only will the rusted part of the plug continue to crumble and
thwart the stop-leak, the rust in the system will conspire with the
stop-leak to block areas where there should be flow and still allow leaks
where there should not. I have successfully used a desperation technique,
though. If you have identified a leaky freeze plug, you can: (1) drain the
system, (2) clean the depression in the freeze plug with Scotch-brite and a
cleaner like Simple Green to remove both grease and water-soluble deposits,
(3) after it dries, apply a liberal amount of putty type steel filled epoxy
to the inside of the freeze plug. If you aren't familiar, they are shaped
like shallow flat-bottomed cups with an inside diameter about the size of a
quarter. What you are aiming to do is to cover the hole by extending the
epoxy from the bottom of the cup up all the sides to the rim, where the
corrosion hasn't hit yet. This isn't foolproof, because sometimes the leak
is actually not through the plug but around it. Still, it is cheap, fairly
permanent, and about the easiest thing to try. Don't worry about making the
plug hard to remove if/when the time comes - they are removed by placing a
punch (okay, everybody really uses a screwdriver) in one edge and whacking
it with a mallet to knock the plug sideways. The epoxy won't get in the way
of that at all. Warning - don't remove a plug unless there is room to use
the mallet to seat a new one! If you do, count on removing the engine to get
to it.

Whatever it is, don't ignore it. Loss of coolant can warp the head and cause
you a lot of grief. If a hose end is leaking, don't mess with tightening it.
It's a safe bet the hose is old enough to merit replacement anyway, and this
should alert you to the possibility of needing other hoses. Any that are
bulging at the end or are hard or squooshy (technical term) need to be
replaced as soon as you can get it done. Putting it off often becomes
forgetting about it, at least in my personal experience.

Mike

 

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They are bigger than a silver dollar, and similar in function to a
paintcan lid. They are designed to pop out if your coolant freezes,
rather than damage the block. That might happen if you had water in the
engine, or weak coolant during the winter. If they ever pop out at
highway speed, all your coolant is on the highway in three seconds. I
saw a VolVo do it Cool

I like VolVo the way Red Green likes the K car.

'Curly'

 

FYI, I used ot have a 84 (or was it 83? It was the first year of that
body style and the one without rear disks) Prelude with the
motorcycle-like carbs and one godzillion vacuum lines. How I hated those!

Ok, I feel better.

If I am not mistaken, the plugs are on the back of the engine. To get
to them the nicest way is to take the intake manifold out. So, before
you do that, get a digital camera/camcorder and see if you can squeeze
it under the manifold and take some pictures of the area. If there is a
leaky plug, do consider replacing it (I would replace all) with brass
ones.