5th Gen - Mysterious coolant loss from expansion bottle?

Edd · Post by **Edd** » Mon Nov 26, 2012 12:21 pm

Are you sure there is coolant in the radiator? If there isn't it'll suck it in when it cools down

arif_manji · Post by **arif_manji** » Mon Nov 26, 2012 1:16 pm

Edd wrote:Are you sure there is coolant in the radiator? If there isn't it'll suck it in when it cools down

Yes, the radiator is full. When I take the cap off, the coolant is to the top. I serviced it 1k ago and drained the complete system out and refilled it with original all season Honda coolant. I remember I filled it up to the maximum and also put some in expansion bottle (to the MAX level).

Supermarine Blues · Post by **Supermarine Blues** » Mon Nov 26, 2012 7:34 pm

arif_manji wrote:
Supermarine Blues wrote:Don't let it get too low; you'll suck in air.

You'll need a coolant sniffer test for HGF. But it could be a tiny coolant leak in a hose, a weepy water pump bearing, or anything at all really.

GLWTSearch...
I had the cambelt changed 1k ago and they guy who did it checked the water pump and said it span fine and didn't need replaceing? I'll keep an eye on the coolant - I'm just hoping it isn't gonna be an expensive fix. Should I get a presure test done?

Bryan, the NSXpert at Norton Way reckons that on those, the WP may go after changing the TB; it seems as if it doesn't like being de-tensioned/re-tensioned. The Harmonic Damper often seems to fail thereafter too. It is thus recommended both are replaced whilst it's all in bits. I dunno if it's the same for Preludes, but it's a thought.

Anyone else had similar?

Supermarine Blues · Post by **Supermarine Blues** » Mon Nov 26, 2012 7:38 pm

arif_manji wrote:
Edd wrote:Are you sure there is coolant in the radiator? If there isn't it'll suck it in when it cools down
Yes, the radiator is full. When I take the cap off, the coolant is to the top. I serviced it 1k ago and drained the complete system out and refilled it with original all season Honda coolant. I remember I filled it up to the maximum and also put some in expansion bottle (to the MAX level).

Ah - I reckon you could be suffering from trapped air. I mean your Prelude...

It can be a bit of a bugger to get the last bits out of the heater matrix, even if you follow the bleed procedure. Try re-bleeding it.

But even if not, that's a lot less to be worried about than a leak.

taz8520 · Post by **taz8520** » Mon Nov 26, 2012 8:18 pm

Have you pressure tested the system ?
Mine was losing coolant slowly, took down my dads put his pressure tester on up to 1.1 bar and started dripping out rad

Post by **Vtecmec** » Mon Nov 26, 2012 8:20 pm

Supermarine Blues wrote:Ah - I reckon you could be suffering from trapped air. I mean your Prelude...

, yes sounds like air just gradually purging from the system.

arif_manji · Post by **arif_manji** » Tue Nov 27, 2012 10:50 am

Supermarine Blues wrote:
arif_manji wrote:
Edd wrote:Are you sure there is coolant in the radiator? If there isn't it'll suck it in when it cools down
Yes, the radiator is full. When I take the cap off, the coolant is to the top. I serviced it 1k ago and drained the complete system out and refilled it with original all season Honda coolant. I remember I filled it up to the maximum and also put some in expansion bottle (to the MAX level).
Ah - I reckon you could be suffering from trapped air. I mean your Prelude...

It can be a bit of a bugger to get the last bits out of the heater matrix, even if you follow the bleed procedure. Try re-bleeding it.

But even if not, that's a lot less to be worried about than a leak.

taz8520 wrote:Have you pressure tested the system ?
Mine was losing coolant slowly, took down my dads put his pressure tester on up to 1.1 bar and started dripping out rad

Vtecmec wrote:
Supermarine Blues wrote:Ah - I reckon you could be suffering from trapped air. I mean your Prelude...
, yes sounds like air just gradually purging from the system.

When I going to work yesterday, I checked the coolant bottle before starting the car and it showed just below MAX. I then got back from work yesterday and checked it after I parked, and the coolant had come back into the bottle and was right to the top? So basically when its cold, it goes down bewteen MIN and MAX and when its hot, it fills the expansion bottle to the top? Is this normal guys? Does this mean there is air in the system? I've had 4 Prelude's and have never noticed this.

Post by **indigolemon** » Tue Nov 27, 2012 10:54 am

That sounds like the correct thing man! Hot engine = expansion = more coolant in the bottle.

ziyaan · Post by **ziyaan** » Tue Nov 27, 2012 11:07 am

when did you change your water pump last. when they go they leak water to give you an indication its time to change.

radiator level

expansion tank means excess water enters when it is hot and there is higher pressure since you cant compress water, it has to leave somewhere, meet the bottle.

are you running that standard 1.1 bar cap or have you introduced a higher pressure 1.3 bar cap. if you have, weak hoses higher pressure will force the water out from a weak spot.

arif_manji · Post by **arif_manji** » Tue Nov 27, 2012 3:49 pm

indigolemon wrote:That sounds like the correct thing man! Hot engine = expansion = more coolant in the bottle.

ziyaan wrote:when did you change your water pump last. when they go they leak water to give you an indication its time to change.

radiator level

expansion tank means excess water enters when it is hot and there is higher pressure since you cant compress water, it has to leave somewhere, meet the bottle.

are you running that standard 1.1 bar cap or have you introduced a higher pressure 1.3 bar cap. if you have, weak hoses higher pressure will force the water out from a weak spot.

If this is normal than brilliant!

I'm running the standard 1.1 cap which was replaced. The cambelt was changed 1k ago and the guy who did it confirmed that the water pump was fine and healthy.