: 94 N* overheating and leaking -bubba move

11-05-08, 08:24 PM
As I've posted recently, a few weeks ago we bought a nice 94 Concours with 110k. We've put about 1k on it with no problems. When checking the oil yesterday I noticed that the upper radiator hose was against the bracket for the motor mount at the bend near the water pump. The corner of that bracket had rubbed a serious looking hole in the hose. It wasn't leaking but it sure looked like it could pop at any time.

So I went out this morning and bought a new upper hose and a new water pump belt. I just took the old hose off and what coolant spilled is all that came out. I replaced the hose and the belt and filled the radiator tank or bottle or whatever it's called. I left the cap off and let it idle for a while and I had to add coolant to fill it up just one time. I didn't _see_ any leaks anywhere. Later this evening we head out to town(we live in the country) and about 10 miles from the house I started hearing a funny noise, a knocking thumping noise. I stop and it's the AC compressor. I turn the climate control off and and on and it quits, but I turn around and start to head back home, about that time the check coolant message appears. Now what? I drive a couple of miles and get to where I can stop and it's wet all over the inner side of the coolant tank. It wasn't leaking on either end of the upper hose I replaced.

We go about a mile and the wife asks if we could get a bite to eat. So I stop at a fast food joint, cut the car off and go inside. I come back out, start it up and head for home. I get about two miles(check coolant light is still on) and I start hearing this thumping noise somewhere near the bottom of the dash that sounds _just_ like a air deflector or flapper door in some old GM truck when you flip the defrost to heater lever back and forth. Then the AC Compressor OFF message came up, then Engine Hot message and then hot engine coolant message.

I happened to be passing a car wash so I wheeled in and cut the motor off. There was no steam and it didn't feel wild and crazy hot. We sat there until the water stopped boiling in the bottle. I checked it, and couldn't see anything naturally. I walked to a gas station about 100 yards down the street and bought a gallon of coolant and distilled water. There was a large wet spot on the blacktop on the inside of the passenger tire. It took the combined 2 gallons to fill it back up the the filler cap throat. I could look and see it dripping on the ground. By that time the car felt down right luke warm and being six miles from home, we hit the road. The car started up, with no messages other than the OK message. The check coolant meesage never came on and I drove 6 miles and it right into the drive way.

On the way home I got to thinking about the days events. It's never ran hot in the almost 1000 miles we've put on it. I've never even gotten a whiff of coolant. The day I replace the radiator hose, it's leaking coolant and gets hot. Obviously something I had done is wrong with the car.

When we pulled into the drive I left it running and ran and got a sheet of cardboard that was close by(doesn't every one keep a sheet of cardboard handy?). I put it under the car(we have a gravel driveway and by now it's dark) After I had put the cardboard under the car, I went in for a minute and came back out and looked at the cardboard- it was dry. Son of a gun! How could that be?

The coolant's not leaking from the upper hose and so I start thinking, maybe I didn't get the cap back on good. It was leaking from over in that area somewhere. I'm 35 and I've took off and put back on countless radiator caps in my time, but it's over there against that strut tower and that fender brace or right beside it too. It makes it a little hard to get the cap off and on.

I took the cap off and there was coolant at the top. It took me a minute to get it back on good and I bend down and look at the card board, and it's wet in a big spot just like the blacktop at the carwash. I fight with the radiator cap and when it finally stops turning I notice the arrows on the cap were lined up with the overflow tube. I think earlier I had just lined the arrows up perpendicular to me like it would normally be on a normal car with a normal radiator. I was standing on the passenger side, the arrows would have pointed parallel with the car, not pointing at the overflow tube. I flip the cardboard over let it idle for 10 minutes. I check the cardboard and it's dry. There's nothing dripping like I saw at the car wash when we had stopped.

I haven't driven it anywhere else, but that's what I'm assuming it had to be, the radiator cap. A bubba move on my part. I don't know how hot the water gets before the ENGINE HOT message comes on. That's why I like plain, old fashioned needle gauges. But since I was able to pull right off the road and shut it off, I don't guess that qualifies as real overheating or as in really had for the head gasket- or at least I hope not.

But seems from what I've read, the issue with the N* is the head/bolts lift, causing coolant to leak which then can cause the overheating, not the engines overheating and causing HG failures.

Lesson 1. Be sure the radiator cap is on correctly.

11-05-08, 11:59 PM
It took the combined 2 gallons to fill it back up the the filler cap throat.
You overfilled it. It needs about 2" of head space for expansion. As it heats and expands the excess will be discharged overboard.

11-06-08, 12:09 AM
I learn something here every day.