Intermittent Steam

[VladD]

I've got a weird problem with my Eunos. On a couple of days in the last two weeks, I've had coolant smelling steam coming from under the bonnet of my car on the way into work. I've never been in a position to stop and have a look before the problem then goes away; it only lasts 30 to 60 seconds. I've had a look subsequently but can't see any obvious sign of a leak. The problem never happens on the way home in the evening. About a month ago I had a squeaking drive belt, so retensioned it, and am now wondering if I've now put too much tension in it and that I'm damaging the water pump, but for me that still doesn't explain the intermittent nature of the steam. Any one have a clue what's going on?

[snotrag]

Check your coolant hoses - most likey one is cracked/holed.

The usual culprits are the two hoses running from the back of the head, into the bulkhead where the heater matrix is. Especially if oil has been dripping onto them from a leaky cam angle sensor.


alternatively, radiator. I had a holed radiator that cuased a leak for ages and could I hell find it, only turning up when the car went on a dyno.


I wouldn't ignore it as whatever is leaking slightly is liable to let go one day.

Most leaks will only show up when the engine is hot, the coolant is under pressure.


Edit - last place to check would be the bottom of the engine behind the crank pulley, and down the sides of the sump. A leaking water pump will dribble out here - you often get tell tale dried up coolant marks.
Could well explain your pump/pulley/belt noise too if the pump bearing is on last legs.

Edited by snotrag on Tuesday 20th September 12:27

[VladD]

Thanks for that. My coolant hoses and cam angle sensor are only a couple of years old, so I doubt it is those, but radiator and water pump I'll check at the weekend. It's only a 7 mile journey to work, so hopefully it'll survive until then. I guess I just need to start and run the engine and hope it happens while I'm watching.

[J-Tuner]

Check the tiny hoses going to/from the thermostat - they are a bd to get on and off and they could not be sealing properly due to an imperfect surface - they are near the belts. I had a weep there that only showed up when it was parked for a few days. Had some drops of coolant on my crank overlay.

Also the metal nipples/takeoffs on the therostat can develop cracks at the joins so check the actual housing.

[VladD]

I turned the heater down to fully cold on Thursday and haven't had any steam since. I got home last night and turned the heater up to full with the engine running and watch the engine bay for 5 minutes, but still nothing. I don't seem to be losing coolant either as the rad is still full.

I'll check the bits you mentioned though, thanks.