Is this likely to be anything other than an airlock? [UPDATE: Answer: "No", it was indeed an airlock]

[Benedict.]

I have a newly rebuilt (head by me, bottom-end & assembly onto head by DVA (& me)) 1.8 K-Series.

On it's first and second brief forays onto the road, the water temperature worryingly climbed much much more quickly than previously, sailing well into the 90s within 3 miles. It never previously got into the 90s unless static with no radiator airflow.
I chickened out before it got >100 but it was heading rapidly that way.

The bottom end is mostly new, but the head is as originally removed, just cleaner. THe ECU, induction etc remains the same.

The thermostat is new, same temp rating, with the much prescribed ~2mm hole drilled near the top of the diaphragm. I tested it on the hob in a pan with a thermometer before fitting!

I was sure that the coolant was filled successfully, I certainly seemed to get the quoted capacity in (can't remember what that was now, but it was as per BC probably).
However, I've not been able to employ my previously 100% successful method of filling the coolant, as this involves idling on the drive, jacking, bleeding & filling until the 'stat opens. My choice of running in method prohibits idling as much as possible.

Am I right to assume an airlock, anything else you think I should check for?
I'm pretty sure it's not running lean, as I've had it slightly lean before (low fuel pres. due to regulator problem) and as a symptom it refused to blip, only increasing gradually. It blips OK at the mo.

All advice gratefully received
Cheers,
Ben

 

 

 

[Paul Richards]

Is the bottom hose getting hot? If it is not it would indicate that the thermostat isn't opening and this is most likely because of an airlock.  

[John Vine]

Sounds like an airlock to me.  Do you have a T-piece in the top heater (or bypass) hose?  If not, there's some good advice here.

JV

[Benedict.]

Yup, got a T-piece in the top hose; I use a mod'd 2L pop bottle with a bit of garden-hose and gaffer-tape as a makeshift funnel for filling from there, so it wedges in and slowly fills. Maybe I should bin this, so air can come out of here as well?

Thanks for the link, I've pretty much done exactly what Andrew recommends in that post, which is why I was confident of a good fill. I might just (re) check the 'stat, then re-fill doing more squeezing.

Cheers,
Ben

[Benedict.]

Wouldn't you just know that some idiot neglected to check that is his annoyance that it wasn't going smoothly! 

Cheers,
Ben

[SM25T]

All hoses getting hot is a sign that water is circulating Ok. A cold hose suggests an airlock.

[21jigsaw]

Thermostat wrong way round?

[Jonathan Kay]

Any magic tricks, or just more of the same?

Jonathan

[Benedict.]

Temperature now stable, so looks like it was indeed an airlock despite my initial meticulous care on filling.
The 'stat was indeed the right way round - I had to check(!), and I (re) tested it in a pan with a thermometer as well.

Interestingly (for me anyway  ), the new stat opens a good few degrees later/hotter then the old one, even though they're both marked 82-degrees. I've stuck with the new one, as it looks slightly better made than the old one, and opens to a slightly bigger aperture, not that matters, I'm sure.

Now to the business of getting it run in - had a good few miles in the sun this morning  

Cheers and thanks all,
Ben 

EDIT TO ADD: Forgot to say, just refilled it taking even longer and with more meticulousness and hosey squeezing than last time and that bit seems fine. I'm sure there'll be more teething troubles though...

[Jonathan Kay]

Well done

Jonathan

[revilla]

Glad to hear you are back on the road Ben!