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Water temp AGAIN!!!!


Red SLR

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This is starting to bug me now.

 

Today I took the car out for a quick spin, 5 miniutes into the drive the water temp was at 120c. This has not happend before so quickly.

 

The header tank was full and steam was coming out of the pop off valve.

 

The radiator was hot, but the exit hose was stone cold, the intake hose was hot.

 

What is going on??? Water is flowing round as the header tank filled up, is this correct?

 

I give up!!!!!

 

Simon

 

1600 K

 

X777CAT

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You could check the thermostat (didn't you change it recentlyquestion.gif) and the water pump to see if they are working properly....

Don't K series car's have a bleed valve in the top hose/rad somewherequestion.gif ( I'm not a 'K' expert, but the cossie engine is prone to air locks, so I have some experience.....)

As for an airlock, I always seem to find that running the car up to about 90-100C with the header tank cap off seems to help, but I couldn't tell you why. If you jack the car up, you need to make sure that the header tank is higher than the rad, so you may need to remove it from it's mounts and hold it up/support it somehow (a girlfriend is quite useful for thisblush.gif) You could also try driving round the block until up to temp, then stopping and SLOWLY removing the header tank cap, but be VERY careful 'cos if the air is loose, it will come shooting out along with some boiling coolant. You get some warning, 'cos they tend to gurgle quite loudly, but be prepared to get out of the way, sharpish..........good luck..........

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The thermostat is under the induction (front TB in your case), it sounds to me like air in the system, jack the car up as high as you can with the engine hot, undo the radiator bleed screw after releasing the pressure in the system then pour hot coolant in through the bleed hole using a funnel and allow all the air to escape slowly, keep topping up until coolant brims out of the hole, leave for 5 mins and top up if necessary, then replace the drain plug.

 

Oily

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When I wrote head gasket, what is important is the seal that the head gasket makes between the block and the head, so there are three components in the sandwich that have to be considered.

 

The liners are cast iron. The head gasket compression ring is steel. The head is aluminium alloy. If there is a problem with the head gasket it tends to be that the head has eroded, warped or softened. Most of these conditions come about through inattention in assembly or localised overheating because of air pockets. The head erosion can be because of an inappropriate coolant choice.

 

IIRC, Simon, you had air locks when you first did your throttle body conversion because you didn't have a vent hose from the throttle bodies up to the expansion tank.

 

I hope it isn't the case, but your problems may have started then.

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I'm afraid it is not quite as simple as that. Without the air return pipe, you possibly need to be more thorough with the bleeding of the cooling system. If you didn't pay appropriate care to the bleeding and everything would have run OK if you had, then your chances of making a liability claim stick are small.

 

But we are getting ahead of ourselves...

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QED fed me the same line. I think the head relief pipe may not be necessary but it is sensible particularly if you have a sticking thermostat.

If your top hose is hot and the outlet cold there is no circulation via the thermostat. Take it out (remove the water pump cover ccomplete with hose as the hose is a pig to get back on in situ) and see if you run without over heating.

As Peter says K series do NOT like being cooked even for short periods but you need to find the cause before repairing the results

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Simon the problem could be a blocked return to the header tank. This is normally the valve in the inlet manifold which is behind the metal tube on which the pipe is fitted. You should take the manifold off but you can clear it by poking something like a thin screwdriver down the pipe. You can check this if you pull off the pipe from the header tank and take the cap off and blowing down the pipe. What happens is that as the water gets hot and expands the water at the top af the head cannot get to the header tank and starts to boil giving you air in the system.
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Update!

 

With the help of JohnE my car is now running cooler. Thanks John.

 

We took the old stat out and put in a new one, the problem was the car was still running hot, about 110c. So we decided to take the stat out, the car now runs at 70c and about 80c when really pushed, which is better than the 120c I used to see.

 

John and I are also under the impression that the head gasket is ok.

 

The only problem I have now is that the car takes about 15 mins to warm up to about 70c.

 

Any ideas on which stat to get? Also I had problems with the hose that goes on the end of the stat case, it keeps slipping as the housing is tapered, anyone had this problem?

 

Ta

 

Simon.

 

X777CAT

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  • 2 weeks later...

Final update I hope!

 

I rang Caterham the other day and also went to see John Noble about the temp problem.

 

I have now sorted the problem by fitting a 3rd stat supplied by caterham.

 

Also changed the fan switch again as that was not working.

 

So the car is on its 3rd stat and 3rd fans switch in 12 months!

 

The car now runs at about 82c which is much better than before.

 

Simon.

 

X777CAT

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hmm, well all was well with my water until today....

 

Drove approx 10 miles with temp at 83c, then stopped to meet a friend and within 60 seconds of being stationary the water temp was upto 120c and water was gushing from the header tank. (fan fuse had gone so not coming on which made things worse.)

 

The only thing I can think of now is the thermostat is in the wrong way round. I returned home and replaced the fuse and bleed the system. This kept the temp down but when I stop at lights the temp goes up again to about 110 - 120c....

 

X777CAT

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Stop risking it, Simon.

 

Run an override switch on your fan so that as soon as you come to rest you can flick a switch and stabilise the temperature. If you wait for a technically correct solution using standard Caterham fan switches you will probably wreck the engine.

 

Simplest way is to get two of the spade connectors which have the extra tag on them and crimp onto a pair of wires run back to a switch in the cockpit. Remove the existing two spade connectors from the radiator mounted fan switch and mount them onto the pair of spades that you have just prepared. Hook the whole lot up to the radiator switch.

 

If through miraculous intervention, your radiator fan switch does work, the temperature will stabilise automatically. If it doesn't work you just flick a switch. Easy!

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