Rep Power: 169

How do I tell which radiator cap is the right one? I know there are 2 types for my car. One has a larger washer under it, almost an inch in diameter, the other has a smaller one, maybe a centimeter in diameter, but both are rated for the same PSI. How do I tell which one should be on the radiator?

Also, what could happen if the wrong one is on? I mean besides overheating in general, what specifically would happen?

 
Rep Power: 812

campare it to the old one? all sorts of problems can happen with the wrong cap. make sure its rated for the same pressure and looks the same as the old one.

 
Rep Power: 518

There are really only two choices for this general size of cap, pick the right height.



I really don't think they can swap at all (slightly different diameters as well as height), but SOME people can go to an awful lot of trouble to screw up something simple.

Oh, this says only a 1mm difference in diameter. No wonder it ALMOST fit!




The 8 or 12 mm depth of the radiator neck determines which cap you need.

HTH

 
Rep Power: 169

TY Ezone, very informative!

The radiator I bought is a Wiggley's 1290. The Type A cap came with it. I tried to find the exact specs for it, but they only list the core size on their website, and mention nothing about the cap size required.



I have the Type B on right now, but just 30 min ago I went to check the coolant level after the car had cooled and when I popped the cap, it was under crazy pressure so that must be the wrong cap.

The reason I put the Type B on is because it seemed that the Type A was blocking the little hole that allows coolant to return to the radiator from the overflow tank, but thats just a theory I had.

 
Rep Power: 518

Pressure buildup as the engine gets warmed up is completely normal.

The correct cap vents excess pressure at whatever is listed on the cap, usually about 15 PSI.


I have also seen cheapo radiators that don't have the neck cut correctly, NO cap fits right.

 
Rep Power: 169

Okay get this:
I just went to go take off the Type B cap. The car was not totally cooled but had been sitting for almost 2 hours and its 60 degrees outside. The engine was only like 80 degrees and there was an extreme amount of pressure in the radiator. BUT, the coolant lvl was all the way to the top.

But that kind of pressure in a cool radiator does not seem normal, it was like I pulled the cap while the car was running and hot.

So I put the type A back on (the one that came with the radiator) I'll drive the car home later tonight and then check the coolant lvl in the morning before I go to school and I'll report back. Hopefully it will be full, but my experience so far with the Type A cap is that is does not allow coolant to return to the radiator, or so it seems.

 
Rep Power: 518

Still sounds normal to me.

The cap that came with the radiator SHOULD be correct for it.


It got a radiator: Did it overheat and blow the head gasket?

 
Rep Power: 169

No, the HG seems fine, I did a compression test today and all cylinders were around 180 psi, a good sign. The car has been overheating, but I never let it get to the red. I actually have another thread going on another site that explains the problem I've been having with the car and the steps I've taken to try to fix it, heres the link:

http://www.hondacivicforum.com/forum...already-94101/

 
Rep Power: 518

Without bothering to read any more than half of that post, I'd say you probably could have blown the head gasket. It doesn't take much of an overheat to do damage.


Ok I went and read a little more.

That screams head gasket to me.
Compression test is not the right test.
I apply shop air line pressure to each cylinder to check, while watching for coolant to rise in the radiator.

HTH

 
Rep Power: 169

So it is actually possible that the HG could be blown even though there is absolutely no oil getting in the coolant and no coolant getting in the oil?

There is no fluid exchange at all, I am positive of this.

 
Rep Power: 518

Absolutely.


You just listed (above) only two ways a head gasket can fail, out of maybe 8 I can think of off the top of my head.

Just because it passed one test, doesn't mean it isn't bad. It only means you didn't run the needed test.

 
Rep Power: 367

oh, there's fluid exchange for sure, but this is the gaseous type.
the liquid type happens in the D-series only when it's reeeealy blown badly.
here we go again...

https://www.civicforums.com/forums/3...reference.html

^ above posted is a link. ignore the guys asking questions and read all the way to the bottom. I compiled most of the info that pops up from here and then to cover most of the cases, so should have most of the causes in there.

 
Rep Power: 169

Well **** me...any idea off the top of your head how much an average shop would charge to do an HG job?

Just ballpark it.

 
Rep Power: 367

no idea, i did myself :P

 
Rep Power: 518

And I don't do numbers.

I couldn't sleep at night if I knew how much this stuff cost in the real world.


You should take the time to prove the issue before tearing into it.
I know I have posted my method several times in the forums here.

 
Rep Power: 169

I'm guessing over $1k. It costs $500-$600 just for timing belt and water pump and I know HG is 3x the labor. I guess I'll call and get quotes for that combustion leak test.

Thanks guys. Even though your news makes me feel sick.

 
Rep Power: 518

Most places will only use the blue liquid method (store bought combustion leak detector), and might give you a pass because it isn't 100% foolproof.

Most won't do what I do to actually prove the problem and identify exactly which cylinder(s) are the problem.

 
Rep Power: 169

So I checked the coolant lvl, it was down about an inch. Not a good sign.

I compared the old radiator opening to the new one and they look damn near identical, it seems weird to me that the Type A cap is the right one. But I'm pretty sure the Type B cap is not venting excess pressure so it cannot possibly be the correct cap.

I called a renown mechanic shop here in my city and they said they'll do a leak down test without having to remove the valve cover as well as check the pressure of the coolant to see if the water pump is turning like it should be, but they can't get me in until Tuesday.

 
Rep Power: 169

I drove the car anyway because I have to go to class...its about 8 miles to the campus and I can take the freeway for most of the distance or go through city traffic. So I went through city traffic on the way, wanting to avoid the freeway on ramp. Had no problems. Car reached normal operating temp and stayed there.
On the way home from class I decided to test it on the freeway. Car reached normal temp and stayed there. It is only 80 degrees outside, so maybe thats why. Just wanted to log the info.

 
Rep Power: 169

Just got a call from the mechanic shop, the car passed the combustion leak chemical test with flying colors. I asked them if they made sure to do the test when the thermostat was open and they said they did.

They recommend I take the car to a smog shop and have them "sniff" my radiator for signs of hydrocarbons but the mechanic said in his honest opinion, my HG seemed fine.

I am not having to replenish coolant ever, which is another reason he doubts the HG is breached.

So now I'm thinking the car is not actually even overheating, I guess I'll replace the stupid overpriced ECT sensor, but maybe its a problem with the gauge cluster?

I'm gonna do a test, run the car really hard, get the temp gauge up high and then check the top radiator hose with an IR gun to see if it's actually reaching temps of over 200. The last time I checked I only saw it reaching 195 even though the temp gauge was elevated.

 
Rep Power: 169

Nevermind. The HG is blown or head is cracked.
Had a smog station sniff my radiator. Picked up hydrocarbons at 343 ppm.

Even worse, I've probably driven over 1000 miles with it like this, so I'm sure the head is beyond ****ed.

 
Rep Power: 518

Only if you let it overheat.

If it never got overheated, it could very easily be fine.

After the head is off, get it to a machine shop to check it for straightness.

Blown head gasket is common. Cracking a head is certainly uncommon.

 
Rep Power: 169

I've never once seen steam, and its never been pegged in the red, but it's seen 75% on the gauge plenty of times, I'll just cross my fingers.

 
Rep Power: 518

Not good. (I just now went back and read parts of the thread).

Pull it off and have it checked. Let them machine it flat again if necessary.
Will be much better than having to do a head gasket job twice.