Fluctuating Temperature after water pump cx 1.8 k series

[Fridybrydy]

Just had the cam belt done and at same time the water pump on a 1.8 k-series. Before the pump change she ran at 82 degrees C no problem. Now temperature fluctuates between 80 and just shy of the red line. Now from experience of changing the antifreeze 2 years ago and having the same problem, I am aware of airlock issues. Last time following previous posts I bleed the system by removing the hose at the top of the heater manifold. I'm afraid it hasn't worked this time. I've also tried the tip of raising the front of the car as high as possible and bleeding the system from the top radiator hose. Again to know avail. Anymore suggestions? Will the airlock eventually move it's way around the system and somehow self bleed. I am a little nervous when she's running just under the red line. Cruising on the motorway she'll read about 110 degrees C, but riding around down she will start fluctuating between 80 and 120 degrees C and I wouldn't say gradually either.

Letting her run in the garage will see the top radiator hose get hot first with the bottom hose eventually getting hot and then some time after that the fan will eventually kick in. During this process I will see the header tank fill from the max line to almost blowing out through the header tank cap. What is the direction of flow of the water? I assume the thermostat is opening as the bottom hose gets hot. Just a point to note, my temperature sender wasn't working when I got the car back but noted the single cable to earth had been detached which I reattached and the gauge now reads fine. Also, it sounds like the location of my temperature sender may be different from others as it is fitted between the heater manifold hose and the hose that disappears under the roller barrel throttle bodies to the thermostat housing

Car is a 2003 Superlight R300 with a R400 upgrade

Kind regards   .........David

[Jonathan Kay]

Do you think that removing the hose at the heater was as effective as fitting a bleeding T-piece?

Next up is massaging the hoses while it's running. Usual precautions.

After that it's drilling a hole in the thermostat.

Jonathan

[Roadsport06]

Bleed tee is worth fitting. Is your heater valve fully open when bleeding?

[SM25T]

Hi David. Long time no see. Bleed tee fitted into highest heater hose is your friend. Search eBay for Caterham bleed tee. Drilling a 3mm hole in upper part of thermostat flange helps air pass through.

If you close heater valve, do the heater hoses to and from the valve get equally hot ? If you open heater valve, inlet and outlet hoses should get equally hot ... if not, there is air in the heater.

[Fridybrydy]

Thanks lads, looks like the Caterham bleed tee is the way to go. I think its a little bit more perseverance on my part. While awaiting for a Caterham bleed tee to arrive. I'll have a bit more play about tickling the hoses and following your sound suggestions.

Many thanks David