B18c running hot

[ringo]

Hi all,

I'm having some cooling issues with my EK which we recently swapped a B18c into. It's a bit long, but I wanted to include all details.

If I show it some brief VTEC love (1st through 3rd gear), the temp guage will rise quite quickly above normal. I can keep it under control by putting the heater on full (comes back down to normal eventually). It does the same thing during highway driving (100km/h) in 5th gear, but it doesn't do it so much during city driving.

When it gets hot, I pull over and notice that the bottom hose is cold (so thermostat is closed) and the fan is not on. The bottom hose is also hard to press, like its full of air. So I replaced the thermostat, but it didn't fix it. Then I thought maybe it was just a dodgy signal from the ECT sender. I swapped that with my old D series one, but it does the same thing.

I fitted an EK9 cluster with the swap (about 5000km ago), so I put my old cxi cluster back in, thinking the gauge itself was possibly shot. Again, no joy.

Here are some other relevant details:

Radiator - brand new aluminium twin core job - doesn't leak, not blocked, with new CPC cap. The radiator gets plenty of fresh air too (not obstructed at all).
Water pump - brand new Honda pump
Thermostat - replaced. The thermostat does open up eventually
Fan switch - turns itself on and off
Cooling system - no leaks. Have flushed several times (twice with a trade strength flush). Water flows in and out through the head. Have tried bleeding several times.
No ECU codes
No milky oil

Does anyone have any ideas? I'd really appreciate anything, coz I'm all out. My next step is to get a water temp gauge, which should tell me if I actually have a problem, or if the car is playing tricks on me.

Thanks for listening.

Joel

[Super-DA9]

What sort of coolant are you running?

[ringo]

None right now, I gave up using coolant. Flushing $38 bottles of Redline Water Wetter gets expensive. I won't be running coolant until it's sorted out.

Cheers

[Super-DA9]

haha i know EXACTLY what you mean. I'm trying to fix these bloody leaks in my cooling system and every time I gotta buy a whole 5L of performance 100 coolant, fkn expensive, annoying and repetitive ay?

what about the raiator? is it a full size like what the DC2 runs, or a half size? because I rememeber someone on the forums here was having overheating issues with his integra because the radiatior was too small.

just brainstorming here :P

[bennjamin]

if the bottom hose is cold- there is no coolant circluating from the thermostat and to the radiator. The thermostat opens automatically when it reaches a certain tempreture - in no way linked to anything electrical in the car. There is a chance you have replaced it with another dodgy one ? The size of a radiator , within reason - should no way alter how cool a engine is kept. The thermostat opens when it needs to , which when it does the thermo fan goes on as well as it circulates coolant thru the radiator and back into the head.If the radiator is slightly smaller then this happens more often. bigger it happens less often etc

[ringo]

Super-DA9 - radiator is half size, but dual core, so it should be good enough. That's what EK4s run anyways.

Bennjamin - I understand. The way I see it is either (a) you're right, and it's a mechanical fault (e.g thermostat), or (b) there is no problem at all, but my gauge is trying to trick me. It's unlikely that it is the thermostat, since it's the second brand new one. I can't rule it out though. But that doesn't explain why the fan isn't on. The bottom hose eventually gets warm, and the fan cuts in soon after.

Thanks for both your help.

Joel

[bennjamin]

couple of things - have you bleed all air from the system ? And , are you using the correct radiator cap ? (correct psi) ?

[ringo]

These are 2 things I'm unsure of. I've have 'tried' bleeding the system several times, following the procedure in my DC2 manual: fill 'er up, crack bleed bolt until steady stream of water comes out, cap at half mast etc. Are there any special tricks here?

The cap I'm running is a CPC 560-90 13psi. I just checked the DC2 radiator, and that has a 16psi cap I believe. I pretty much just matched up a cap to the radiator, since the one is came with was rubbish, and that was the closest I could find.

[Glocker]

take cap off, start engine, turn on heater on full blast, then wait for the fan to come on at least TWICE before putting radiator cap on. this will flush away the bubbles in your system.

[string]

Surely the bottom hose being cold simply means that the radiator is just doing it's job properly? You did say that it's a fancy aluminium job and that you've tried a couple of thermostats. The coolant flows from the head, to the top of the radiator, then out through the lower hose after being cooled.

If you want to know for sure, take out your thermostat. It'll take ages to heat up but you'll quickly find out whether or not you have a far more serious problem. I hope that you don't have what happened to me a long time ago: a cracked sleeve which leaked combustion gasses into the cooling system and heated it up like crazy.

[ringo]

Yeah, fingers crossed. Actually I think the thermostat lets water out of the motor (not in), so water flows from the radiator to the head, then back out through the t/stat and through the bottom hose.

I must confess, the radiator is a cheap ebay one :p

Cheers

[Bludger]

coolant flows into the radiator via top hose and out via bottom.

[egb16b]

It's strange that it does it during highway driving and not city driving.

To me it sounds like thermostat but since you've already changed it then maybe not. Are you sure it's in the right way?? You may have installed the wrong way and so it's not opening properly.

[ringo]

I think it's strange as well, and annoying. Thermostat is definitely in the right way.

Cheers

[rhys.l]

Few possible ideas after researching the b18 cooling system myself recently. Take them with a grain of salt because I still don't really know what I'm talking about :P

- You said the ECT switch is alright and you replaced the sending unit but what about the ECT sensor (right near the sending unit)? Could it be part of the problem?
- Instead of buying another thermo, test the one you have. Put it in some water and see what temperature it opens at. Should be around 80C by memory

[bennjamin]

Replace cap with proper 1.1 bar (16psi) radiator cap - a new one !

Next , from cold start leave the radiator cap off turn on engine slide the heater to HOT and let it idle for 15-20mins until the rad fan goes on TWICE. as this happens air bubbles will be plopping out and the level will be dropping - so top it up. After fan comes on twice turn off top up put cap back on then make sure the overflow is filled and sealed too. Drive as per normal and that should be all air out.

[dougie_504]

If the fan doesn't come on (happened to me last 3 times and they're not all broken lol) then squeeze the top hose a bit to get some of the stubborn air out and just re-fill your overflow reservoir as necessary.

[Lerlo]

IMHO bottom hose should not be cold during operating temperature.
Try running the engine without the thermostat, see if it still overheats.
Also, when its at operating temperature, open the radiator cap carefully with a towel and see if water spills out. If its air that comes out, then your cap is not working.
I think your system has lotsa air in it or maybe your water pump is gone?

*edit* Just saw new honda pump...

[ringo]

Thanks for all your input. I've just put a new 16 psi cap on. Will give it another flush and see how it goes.

Cheers

[Benson]

Remove the thermostat. If it still overheats, radiator could be block, or you got some other bigger problems

[ringo]

Radiator is brand new and is not blocked. It now has the 16psi, 1.1 bar cap. I've bled the system countless times. It seems to keep getting air in it. Bottom hose is always hard and cold when the gauge reads hot (after driving for example). Occasionally there are bubbling noises from the top hose. This happened earlier today, so I cracked the bleed screw and air gushed out for a minute of so. I top the coolant up, but it always happens again.

I'll remove the t/stat tomorrow to see if that makes a diff. But I'm starting to fear the worst. I'm hoping it's nothing as serious as a cracked block (as string mentioned). That would suck the fat one.

Should I consider a 1.3 bar cap? I've noticed that the caps that j's, spoon, mugen etc produce for aftermarket radiators 1.3-1.35 bar caps.

Cheers

[anjin]

Two water paths.
Initial one is head - pump - pipe along back of engine - past the closed thermostat - head. Or reverse of that - I can't remember which way the pump flows.

Second additional path is when the thermostat starts to open up and some water flows through the radiator instead of past the thermostat, and then back to the head. The more the thermostat opens the more flow goes through the radiator.


I understand that your fan is coming on, but the bottom hose is still cold. Assuming that the fan is controlled via the engine temperature sensor (I am used to engines where the temperature control is in the radiator), then the head is hot, the fan is on, but the thermostat isn't opening.

So the options I see are that you have a blockage somewhere, there is a big air bubble in there, the thermostat is installed wrong (upside down - the little valve has to be up) or faulty; or maybe the temperature sensor is switching the fan on way early and the engine isn't getting hot then.

You can test the thermostat and temp sensors in a saucepan on the stove. Need a multimeter for the latter.
The flow you should be able to see by removing the thermostat as already mentioned, and leaving the cap off.

And yes - I'd like to see real temperature data as well.

After that it gets specialist radiator testing time.

[zropts]

What ECU you running by the way? Have you checked fuses? also are the fuses the correct ones for each slot? Woulnt hurt to check.

[Glocker]

Radiator is brand new and is not blocked. It now has the 16psi, 1.1 bar cap. I've bled the system countless times. It seems to keep getting air in it. Bottom hose is always hard and cold when the gauge reads hot (after driving for example). Occasionally there are bubbling noises from the top hose. This happened earlier today, so I cracked the bleed screw and air gushed out for a minute of so. I top the coolant up, but it always happens again.

I'll remove the t/stat tomorrow to see if that makes a diff. But I'm starting to fear the worst. I'm hoping it's nothing as serious as a cracked block (as string mentioned). That would suck the fat one.

Should I consider a 1.3 bar cap? I've noticed that the caps that j's, spoon, mugen etc produce for aftermarket radiators 1.3-1.35 bar caps.

Cheers

Recurring air bubbles? Uh oh....gases from your engine's head might be leaking into the water; check your head gasket. I had the same problem and my top radiator hose blew up in the middle of Newcastle freeway. It came from being overheated once by my girlfriend and the mechanic thought it was fine...If your engine is old you might wanna check this.

[ringo]

Running a OBD1 P72 ECU, all fuses seem fine last I checked.

Today I removed the t/stat and did a comp test. Haven't driven the car yet, so it hasn't overheated. Air bubbles do not stop even after extensive bleeding (50+ minutes).

Compression varies quite a bit, but is within the 20psi limit.

Here are the results, roughly:
No 1 195psi, 1350kpa
No 2 185psi, 1275kpa
No 3 200psi, 1375kpa
No 4 210 psi, 1450kpa

These are well within the minimum 140psi, 930kpa.

2 things I noticed today:
(i) some water is coming out of the exhaust - it's pretty mild weather here in Perth, but it still did it once the engine was warm
(2) my plugs (<5000km) are quite fouled, and the ground electrode is fairly white. I think this is consistent with a blown head gasket (some oil getting into the combustion chamber/engine getting hot).

Will post again once I drive the car. Then I think my next step is to do a leakdown test.

Cheers

[ringo]

It stays very cool w/o the thermostat, yet is still pushing lots of water into the overflow tank. I will do a leak down test after exams have finished. Will update post afterwards.

Joel

[Lerlo]

It stays very cool w/o the thermostat, yet is still pushing lots of water into the overflow tank. I will do a leak down test after exams have finished. Will update post afterwards.

Joel

So without the thermostat, i assume the bottom hose isnt cold anymore? Pushing water into overflow tank sounds bad, how much water exactly. Its normal for the water level in the reservoir to rise by 1-1.5 cm when at operating temperature due to increase in volume of heated coolant, but it is overflowing the bottle and you can see bubbles, then it sounds like HG problem

[ringo]

That's right, bottom hose is warm now. The engine doesn't get to operating temperature, but is still pushing at least a few centimeters into the overflow bottle. It's not overflowing.

At this stage I would be super happy if it was the head gasket. I will do a leak down test next week and maybe use some Teekay head check to see if there are exhaust gases in my coolant.

Cheers

[ringo]

Ok, I've done a Teekay head check test and it was negative. Kind of frustrating, because I was almost certain there was a combustion leak there somewhere. Still haven't done a leak down test though.

[Bludger]

so, any news?

[ringo]

Not yet I'm afraid. I got busy with uni and stuff. I have a leak down tester on the way. I'm leaning towards a head gasket, despite the tee-kay head check. Will update once I've done the test.

Cheers

[bigjo5]

take out your spark plugs , you can get a torch and shine it down the combustion chamber, most of the time if your headgasket is gone, you'd be able water on top of the piston, try that =]

[ringo]

Thanks for that. The no 3 cylinder appears to have a little moisture in there. The pistons are very black.

I'll know more in a week or so, once I do a leak down test.

[whitecomet07]

im having this problem on my car too. car is stock EG5 VTi. i changed fan switch and temperature sensor. my car also heat up when i drive. if i turn on the heater the temperature drop back to normal. will be keen to see what problem your car has.

[whitecomet07]

any update on this?

[jdm18c]

dose the top and bottom radiator hose heat up or are they the same temp when hot??

[ringo]

No update right now. Leak-down tester is still on its way. Next step will likely be ripping the head off.

Top and bottom hoses get hot now, but there is no thermostat in the car. When the thermostat was in, it was as if an air bubble prevented the thermostat from opening or letting coolant flow through. With the thermostat in the car, the bottom hose stayed cold after driving (but would heat up at idle).

Will post as soon as I have more info. I appreciate the interest guys. Thanks.