Cold bottom rad hose

[tonydgray]

Hi all

I've recently swapped out my old B20a engine for a second hand B20b engine. The engine seems to run fine but the temperature does climb quite quickly in traffic and also sits a little warm under normal driving conditions. If I put the heater on it makes it run a little cooler. After a decent journey I noticed that the bottom hose is quite cool and the top hose seems to have some pressure in it. I worried the water is not circulating around the system.

Is this likely to be the result of an airlock or blocked radiator?

Thanks

Tony

[Leeds Lad]

Poss airlock, from cold, start the car up with the rad cap removed from the header tank and just let it tick over, eventually the air lock should work its way through.
But before this is done I would replace the Stat to test.
What should happen, once the stat opens the air lock should come to the header tank and all water disappears from the tank, just keep watching the water level and top it up as you go.
It may be worth also flushing the system with the stat removed, just put a hose into the top rad hose and it should flow out the top of the rad, if it blows back you have a blockage, just eliminate by disconnect hoses in sections.
Good luck.

[Derek UK]

If you've not checked the thermostat on this, possibly unknown, engine that would be worth changing as a matter of course. Don't forget to have the heater on full hot when you bleed the system, so that that the air in the heater matrix can get displaced.

[Billy Smalls]

Definitely change the thermostat and don't get one from Halfords!!!

When you are 'burping' the system of air, give the top and bottom rad hoses a good squeeze - like you're milking a cow!! (i've never milked a cow)

[arcturus]

Also hang the expansion bottle up above rad height and eliminate any U bend in the pipe. When I refill my system I open the engine drain tap untill water flows from it. That does help to get rid of some air.

[tonydgray]

Thanks everyone. I've had some time to work on the car today and I've found that the radiator is all fowled up inside and hence restricting the flow. I've purchased a flushing kit and it seems to have helped. I'll have chance to take the car for a run tomorrow to check how its doing and I'll update the post following that.

Oh, I also now understand about burping the system, thanks again.

Cheers

Tony

[tonydgray]

After performing the radiator flushing yesterday the system seems to be working a little more efficiently which can only be good. After burping the system the original problem of the bottom hose being cold has also gone so a step in the right direction. I used the two step holts rad flush from halfords.

As it stands now, if the car is left ticking it won't overheat whereas I got the feeling that it would have done before, again this is good. The temperature on the gauge has always been bang in the middle since I've owned the car and only really got hotter in traffic after a while but its always coped with the heat. After driving the car this morning I realised that the heater was still on hot inside so I switched it to the coldest setting which unfortunately resulted in the running temperature increasing to the just below the top part of the green section which is not ideal.

At the moment I can't really afford to have it re-cored or get a new one so ideally I want a really good radiator flush that can clean it out even more and hopefully buy me a bit of time.

Thanks

Tony

[Derek UK]

Make sure your rad cap, on the bottle, is good. If it's leaking it won't keep the coolant under pressure and that is what raises the boiling point. Monitor how the coolant level goes up and down hot/cold. Shouldn't be much. As you've been flushing the system you'll need to keep an eye on the levels for a few days anyway. Before you shell out on a new one rad, take this one out and back flush it for a while. Give it a good shake now and then while you're doing it.

[tonydgray]

Thanks to all who have helped with this problem so far... a quick update:

Briefly put, I've now got a new rad on the car(a 240 one fits) so radiator flow should not be a problem but it still runs hot and in all honesty the rad has not made any difference.

One thing I have noticed is that I don't think the water is being pumped around the system. The reason for me saying this is that when the car is left ticking over it copes with the heat ok and the temp is around normal. Felling the bottom hose its not cold but mildly warm. When driving the car the heat rises to higher than normal and can only be brought down to normal but introducing additional cooling but pushing the heater lever over to warm(not turning the fan on though, just the valve).

Here is the strange part. After test driving and pulling over as the temperature had risen I popped the bonnet and took a quick look. I found that the bottom hose was cold and the top hose was hot so I gave a few quick squeezes on the top hose and the bottom hose then got warmer. I took a quick look at the temp gauge and that was registering normal. I then jumped back in the car and drove home another couple of miles and the temp started to rise again. At home I popped the bonnet, checked the bottom hose and low and behold it was cold again. It seems to me that the water needs to be manually pumped around my cooling system.

I've got a new thermostat from brookhouse but I've also switched it with the old one and my symptoms are the same so I've ruled that out. I've bleed the air out of the system by raising the bottle and burping it so I've pretty sure the there is no air lock in there. The water pump on this engine actually looked fairly new in appearance and the vanes appeared to be fine so I can only assume that it would pump ok.

All in all I'm now at a bit of loss as to what the problem could be so any help at all would be great!

Thanks in advance

Tony

[arcturus]

When you say "new rad" do you mean new as not used or new as different but old? If the later that also could be blocked if it has been standing for a while. Try using "Bars flush"