Overheating Continues...

[mjsstanley]

To make a very long story short, I have been having cooling and heating issues with my lateser CB since I bought it over the summer. First few things I changed was the radiator & cap, reservoir tank, thermostat and coolant temp sensor. Drove for a week or so and started leaking severely, all at once. Then, had a shop change the heater hose (they said they were sure this was the issue). After one trip of about 2 miles, same leak. So I then located the leak myself.. a hose coming from the back/side of the IM. So I bought an entire hose kit and had that installed. All seems good.. until about 10 miles later, car started overheating again. This time, lots of pressured steam from the reservoir tank. Took that out, and located a small hole. Ok, took care of that. Drive the car again the next day, overheats again. This time, pressured steam from the top of the radiator. So now I'm guessing I have to buy a new radiator again?? My thought is that since the hose on the IM was leaking before, with the coolant pressure somewhat normal now it's now leaking/steaming from other places?? Gonna try and upload more videos later.

[sonikaccord]

Is your thermostat installed the right way?
Did you bleed the system?

It looks like you have everything else covered.

[mjsstanley]

I'm pretty sure the thermostat is installed correctly. I've had that chagned twice. Not sure what bleeding the system consists of. I didn't do any of the work myself, had it all done by mechanics. But as the car is right now, there's definitely a very very small amount of coolant sizzling out of the top of the radiator. It doesn't start until the car is warmed up completely, then after I start driving, it overheats.

[sonikaccord]

Bleeding is simply purging the system of air. Air pockets in the cooling system will prevent it from working efficiently.

There is a 10mm (?) nipple on the thermostat housing that is used to purge air. There's a DIY on the site. It is very easy. It is like turning your faucet on, waiting till a stream of water comes out, then turning it back off.

The fact that your car overheats when driving leads to a few things:
Bad Radiator Cap
Stuck Thermostat
Faulty Water Pump (or air pockets)
Blown Headgasket

From best to worst case, of course.

How do the lower and upper radiator hoses feel? The upper should be hot from the engine and the lower should be slightly warm from being cooled by the radiator.

[mjsstanley]

Honestly, when it overheated earlier today, I got out and left it running (temp gauge doesn't quite reach the H but way over 50%). Popped the hood and felt the upper hose which didn't feel extremely hot. After I shut the car off, I was able to leave my hand on the hose comfortable within 5 minutes. Another thing I've noticed, if I crank the car up in the morning (about 45 degrees here in Atlanta), let it run for about 5 minutes, the passenger side fan will come on after shutting the car off. Wont even reach normal operating temp but the fan comes on anyway.

[Fleetw00d]

Do you have an infrared thermometer that you can check temperatures with? When it overheats, do you get really hot air inside the car if you crank the heat up? If you can hold the hose for five minutes with it supposedly overheated, I suspect the water pump isn't circulating the coolant so the only coolant being heated is that in the engine itself. Any idea how old your water pump is?

[mjsstanley]

One mechanic did inspect the water pump and said it showed no sign of failure. When I first bought the car but in June or July (90 degree days), it would literally run at extremely low temps. Gauge would barely reach 25% unless I was sitting still at a red light. It would overheat after a few days of doing this, I would top it of with coolant and the cycle would repeat. This was before anything was changed. Now, when the gauge rises, there a lot of steam coming from one particular spot on the top inside of the radiator. There would also be a puddle of coolant sitting on top of one of the fans. Should I go ahead and have the radiator and reservoir changed again?

[sonikaccord]

Play with that nipple.
We want to verify if coolant is flowing properly.

It sounds like you had a stuck open thermostat initially plus the coolant leaks. I doubt that would've caused any damage unless the engine got really hot.

[EsperHamid]

are the fans working ? the thermostats are chinese nowadays ... they tend to get stuck ... closed: overheating, open: bad mileage. I changed 3 in less than a month before doing the below ( revelation )

some people might kill me if I say what I did to my engine but here I am going to say it anyway. My car runs on a metal disc ( taken from a can of tuna, seriously) cut into a 4 cm diameter and drilled at the center with the "third drill bit size" starting from the smallest bit. using the thermostat gasket of course to prevent leaks at the thermostat housing

it takes 5 minutes from a cold start in the morning, true, but when it is up to normal op temp ... the needle wouldn't budge up or down either in SUMMER or WINTER !!

... of course I had blocked off the air vents on the front bumper and only left an airgap facing the third cylinder top and bottom.

PS: my condenser fan stopped working recently, so I am only running on the cooling fan ( the big fan ) and it is NOT !! overheating even if you climb a hill or go to china

[H311RA151N]

You are building pressure in the coolant system and it's escaping where ever it can.

It will leak at the weakest location. Always. Once you get all the gaskets and hoses on really well it will then push out into the overflow.

The tests for a small headgasket leak is very simple.

With the engine cold. Fill the system with the bleeder valve open. Let it run out a bit. Tighten down the bleeder valve. Pour in more water until the radiator neck is full to the brim. Start the car. Some of the water will blow out on initial start up, very minimal. Let it run. You will see the thermostat open as the water level will decrease a bit. Fill the radiator to the brim again. Where you can see the water. The brim being right beneath the overflow orifice. Watch the water level. You will get an occasional bubble. At night with a flash light you can see that the bubble is actually steam as you can see the steam come off the bubble.

They also have testers that test for combustion in the coolant system.

Another way of telling is by simply pulling the plugs. It's all in the link to my MRT posted below.

If your car isn't hard to start it soon will be. You have to let the pressure escape. This is crucial. You want to let the system purge it's self of the pressure as easily as possible. A pin hole in the radiator cap does wonders.

I also had luck with a product from Walmart. K&W something or another. That car with the K&W held together for me when I was in really rough times long enough to get me out of those times. Of course, if you can replace the headgasket then that's the right way of doing it. I'm just going over a few things that will get you by if you are in a tight spot. If you are at all in a position to change out the head gasket then by all means do it.

First have it looked at by whoever you have doing the labor and whatnot. Tell them what I told you. It will point them in the right direction. It either is or it isn't. One or the other. Pretty simple. I hope I'm wrong but I'm just going to go out on a limb here and say that it's very likely the headgasket.

Link to MRT as discussed. http://www.cb7tuner.com/vbb/showthread.php?t=206167


EDIT. Starting on page 15. Finding the issue on post 286. http://www.cb7tuner.com/vbb/showthre...206167&page=15

[G. Wiffington]

are the fans working ? the thermostats are chinese nowadays ... they tend to get stuck ... closed: overheating, open: bad mileage. I changed 3 in less than a month before doing the below ( revelation )

some people might kill me if I say what I did to my engine but here I am going to say it anyway. My car runs on a metal disc ( taken from a can of tuna, seriously) cut into a 4 cm diameter and drilled at the center with the "third drill bit size" starting from the smallest bit. using the thermostat gasket of course to prevent leaks at the thermostat housing

it takes 5 minutes from a cold start in the morning, true, but when it is up to normal op temp ... the needle wouldn't budge up or down either in SUMMER or WINTER !!

... of course I had blocked off the air vents on the front bumper and only left an airgap facing the third cylinder top and bottom.

PS: my condenser fan stopped working recently, so I am only running on the cooling fan ( the big fan ) and it is NOT !! overheating even if you climb a hill or go to china

HAHA what? A Tuna can?

[mjsstanley]

So my overheating is under control after new hose kit, thermostat, reservoir and radiator. However now, car temp gauge does not move from the cold line. Long story short, I've had one overheating issue after the other. Up to now (from August), I've had 3 different radiators, 4 different thermostats, 3 different reservoirs, and a new hose kit. So latest repair has me back in business!

Last radiator, silver prongs started to separate which cause coolant to spit out and caused the car to overheat. Before that, there was a hose on the backside of the IM that was leaking coolant drastically.

Yesterday, I got a new radiator, thermostat and reservoir. So now, that car will not leave the cold line unless I've been idling over 5 minues and even then, the temp gauge barely rises. No coolant leaks whatsoever. Latest thermostat was an OEM Honda replacement.

A well known Honda dyno mechanic stuck a knife in the coolant temp sensor that goes into the front side of the block to see if the temp gauge moved any but no luck. He stated not to worry about it. However, I've owned 5 different CB7s and none have every done this. Passenger side fan will come on after idling for a minute or so. Besides the thermostat and sensor, what else could possibly cause the car to run at such low temps? I literally work 32 miles away from home. Going and coming today (80-85mph) the temp gauge never left C. Any idea guys? The mechanic told me not to worry since it's no longer overheating, but I want a normal operating temp.

[Rilas]

I'd check the connection for the temp sensor gauge. It's just to the right of the engine coolant temperature switch. It's a single wire, it might just be disconnected. Easiest place to start at least.

[Fleetw00d]

Test the Temperature Gauge:
- Turn the ignition switch off.
- Disconnect the single wire (red) from the ECT sending unit (this goes to the gauge).
- Short the wire to ground
- Turn on the ignition and note if the gauge starts to swing toward "H". Turn off the ignition before it reaches the "H" or it may damage the gauge.
- If the pointer doesn't swing, check for an open in the red wire.

Test the sending unit:
- Disconnect the red wire
- With the engine cold, measure the resistance between the positive terminal and engine ground. OEM manual indicates that for 133F (cold?), the resistance should be about 142 ohms. With the engine at normal operating temperature (185 - 212 F), it should be 49 - 32 ohms.
- Based on that range, if the engine is COLD (like 12 degrees in Cincinnati now), the resistance will likely be over 200 ohms.

I have had issues with incorrect readings on fuel and temperature gauges caused by corrosion on the printed circuit board in the gauge cluster as well as bad guages (they can be replaced without changing the entire cluster). If you have or can borrow an infrared point and shoot thermometer, check the temperatures at the thermostat and discharge housings/hoses to see if they are in the correct temperature range.

[mjsstanley]

So temp gauge and gas gauge seem to be operating properly. Car reaches somewhat of a normal operating temperature after steady driving. Yesterday, it started steaming from the head or block somewhere.. not the radiator or reservoir tank. Today, the steam got heavier. Car doesn't overheat. When cranking from cold, car idles but doesn't warm up completely (I have a video or revving the engine to 2500rpm and the temp gauge falls completely to cold) however I cannot upload that video. The pics below show the liquid at the tip of the exhaust and the light white smoke coming from it.... I'm REALLY hoping it's not the head gasket.. Car doesn't overheat, no milky substance at oil cap, and no milky substance at tip of exhaust either. But definitely water and light white smoke. Head gasket? I've changed everything else that I can think of.