405 strange over heating problem after rad change

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405 strange over heating problem after rad change

Post by PeteAJ » 30 Nov 2003, 05:10

Hey Guys and Girls,
Please bare with me, im an IT engineer and don't know much about cars but like to have a go
(I can hear you all shouting Doh! and slapping your foreheads)
let me start by filling you in.
I have just gone back to my long abandoned Pug 405 Style (1.9TDi) and started her up. had been standing out in the cold for about 8 months.
as soon as I started her I noticed water coming out of the rad, apon closer inspection where the leaves had collected againsed, it had rotted the bottom away, so replaced the rad.
filled it up and the car was still over heating, looking a little closer, the thermostat was shot so replaced that.
now here is my problem;
when I start the car from cold it warms up then continues to heat to the point of over heating, the stat is opening (I can feel the pipe getting hot) so, I removed the small bleed lug from the rad (opp side from the filler cap) and put a hose in the other end, then started the car hoping to flush out any air locks. once the car heated up the stat opened the water level of the filler tank sunk (below eye sight) and loads of steam gushed out of the bleed hole, then returned to flowing water. wicked I thought to myself, job done. I left the rad filling while I went to find the bleed cap, when I returned 3 min later I saw the same thing happening. OK maybe there was another air lock, but after 45 mins of this I am beginning to think there is something wrong. the car starts on the key every time, I cant see any water getting into the oil and there is no water coming out the exhaust so I don't think its the head. (well I hope not)
any suggestions as to what this could be ? maybe im not bleeding it on the correct manor ?
thanks in advance]
Pete AJ

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Post by Homer » 30 Nov 2003, 16:00

I don't know about the Pugs but on the Cits the header tank is below the highest point in the system so you have to rig something up to get a head of water. I found a length of waste pipe worked well with a little padding. Then open the bleed screws in turn until water seeps out.
You may have missed a bleed screw as well, look at the piping around the back of the cylinder head.

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Joined: 27 Jul 2003, 16:18

Post by CANDO » 30 Nov 2003, 19:07

I agree with Homer.
The header tank is lower than the highest point in one the engine so you do need to make up a temporary header then extension. I glued an upturned plastic bottle to an old radiator cap. Homers pipe idea sounds a very good and cheap alternative.
I know longer have the car but if I recall correctly there is bleed screw on the top, right hand side of the radiator, which I took right out, one on the top front of the thermostat housing (an Allen key type, 4 or 5 mm) and one a hose that came out of the right hand side of the thermostat housing (I think it ran to the rear of the engine). This bleed screw was a white plastic fitting about five inches along the pipe from the housing with a 1/4 or 1/2 flat screw that you could undo with your fingers, which I also took right out. I think this was the upper most point on the system. There may be others but just using these three and closing each one in turn, (after a good flow of water from it) from the lowest I.e.. Rad, thermostat housing and pipe I never had any problems with air locks. It’s also worth making sure that heater control is set to hot.
I did have a problem after the first refilling in that the engine would warm up normally then rapidly overheat, and the water level had disappeared from view. After refilling twice I then realized that the radiator cap was VERY tight to turn and that I hadn't fully closed it. Consequently as the system heated up and pressurised it simply forced water/steam out of the cap seal. Doh!. Still you live and learn, don’t you?