The other problem with the Argo is that there is some white emulsion in the oil filler tube but oil on the dip stick is fine and the coolant level is always right up to the radiator cap and never needs topping up. This is all a bit concerning so I spoke to Ian at Aird Motors and he just said without any hesitation .... too much cold running, take it out for a good run and get it fully warmed up. So I did this last summer and the emulsion seemed to go away. However I noticed the engine temperature gauge never got above 100F (38C) and that was when going uphill with full throttle. So was the gauge faulty or was the engine never getting hot? So I checked the gauge by taking the wire off the temperature sender and earthing it. The gauge went full scale, so it seemed to be working fine.
Emulsion in the oil filler tube
Oil on the dipstick looks fine
I then decided to check the temperature of the coolant feed to the radiator by strapping a temperature gauge to the top pipe and started up the engine. As soon as I started the engine, this showed an immediate temperature rise but it never rose above 31C. This all pointed towards a stuck open thermostat and to get at this the manual says you need to take out the radiator.
So out came the battery and carrier frame to get at the radiator drain. This is a twist-to-open plastic affair with a nice slot in it to allow slow draining without take the whole plug out. So, very easy to put a pot underneath and let it drain whilst you get on with other jobs. The coolant colour looked terrible.
I then disconnected the air cooling hoses to the disc brakes from their plastic manifold and then took out the manifold itself in front of the radiator as it just gets in the way. I had to remove the air filter to get the top hose off as there was no room to pull the hose off sideways and I also took out the expansion bottle to get at the bottom hose. Once the hose clamps was removed, the hoses came off quite easily with a light twist with some plumber's pliers. The radiator is held on by 4 bolts and when I was taking these off it was obvious that the radiator had been out before as 2 of the rubber insulators were missing. The radiator came out by moving it forward to get the bottom hose pipe clear of the expansion bottle bracket and upwards from there.
I flushed out the radiator in both directions, quite a lot of sludge came out, it all seemed to be in the bottom and freely came out. There was plenty of flow so I was quite happy with the radiator.
The manual says to remove the fan to get at the thermostat but you don't need to and I undid the two bolts of the housing without difficulty and gently pulled it off with the top hose still attached. I can't say I was completely surprised to find there wasn't a thermostat in the housing as one of my friends had said this was a possibility. I'm not very happy about this because you start to postulate why it was removed in the first place. Was it a quick fix to a problem or was it faulty and no replacement was at hand? I just don't know at present.
Anyway I phoned Andy at Aird Motors and he had a new thermostat in stock. I had the foresight to ask him if it came with a gasket, so he opened the box and said "No". I don't know why manufacturers do this as you are always going to need a new gasket for the thermostat. Anyway Andy had them in stock and he said he would post the parts 1st class straight away. Fantastic service. I also has a chat about which sort of antifreeze to use and he said they just use the blue stuff. This has to be changed every 2 years whereas the more modern orange OAT lasts 5 years. I had a little look at info on the web and eventually decided to go for Prestone Extended Life (yellow stuff) which gives 5 years protection and seems to be compatible with all antifreezes and engines and doesn't seem to cost anymore.
The thermostat came the following lunchtime so I set about fitting it. The first thing I did was to test it by suspending it in boiling water to make sure it worked. An old traditional jam thermometer came in really handy here. The Thermostat is stamped 82C but the manual says it's not fully open till 95C. Anyway it seemed to be fine. Fitting was just a reverse of the removal process. The thermostat has a little fiddler valve which is to help get air out of the system and this needs to go at the top. I fitted the bottom hose before the radiatior was bolted back in place as the overflow bottle bracket gets in the way of doing this up. I also took off the air filter again to fit the top hose.
Regarding getting rid of air in the system the manual just says fill the radiator to the top, put the cap on, top up the expansion bottle, start up the engine, let it warm it up, switch off, let it cool and top up the radiator as necessary.
Once the battery was back in I pulled out the choke and started the engine and watched the engine temperature gauge very carefully. I also kept feeling the top of the radiator to see if it was getting hot. It got up to 80C quite quickly ... I'd never seen it get to this temperature ... and the radiator was showing some signs of not being as cold. The temperature climbed to 95C and all of a sudden the radiator was fully hot and the gauge slipped back to 80C. I let it run for a bit and noticed that the gauge cycled between 80 and 95 C. What was also noticeable was that the engine just sounds a lot sweeter than before. I switched it off and let it cool before topping up with coolant. I've done this a couple of times now and it all seems to be ok. I've also had good look around for leaks from hoses and the thermostat gasket but it all seems to be tight.
