Frustrating day....not going to plan at all!

[tony750cc]

I had planned pretty much a day on the stag today putting new header tank, fitting new coolant hoses, stat, temp sensor, and a few bits and pieces.

First lesson, now matter how careful i thought i was being i still managed to get the leads wrong, im amazed it was actually running and didnt sound too bad until i drove it, wasnt happy with 2 leads in the wrong place, bit of head scratching and got that sorted.

Then the fun began. Removed the old expansion bottle and fitted the new header tank kit, bit fiddly with the positioning of the top 90 degree bend as the supplied one was facing completely the wrong direction, quick trip to b and q sorted that. Opened the stat housing....wot no stat! started to get a bit worried by that as suggests to me its been removed to resolve a overheat problem. Fit new stat, temperature sender unit and all coolant hoses, couple of battles with the old clips but all eventually sorted. Fill system and start her up, watched the gauge rise fairly quickly....it kept going and going and eventually stopped around the 3/4 mark which is higher than it did before i started. I then opened the heater valve manually as the cable had seized, lots of heat in the car. Noticed now that the system has pressurised... a lot, the top hose is pretty much rock hard. Both heads dont feel that hot and the radiator itself doesn't feel hot but the water system is pressurising and getting hot the tank is barely touchable. Id put a cooling system flush into the tank hoping to clean the system beofre putting new anti-freeze into it.
Whats my next step? do i suspect the heads or maybe the water pump?? having just spent a couple of hundred quid hoping to improve the cooling system its now worse than it was before i started!
Im hoping this isnt going to be a terminal issue as ive only had the thing a week!
When its running it feels sweet, it pulls really well and doesn't cough etc. im getting scared to use it now

Any thoughts or ideas please!!!

Tony

[Staggard]

Hi Tony, you hav'nt go air trapped in the system , how did you refill the system through the header with the rad plug out ? and the heater on hot and run it up with the header cap off to let any trapped air excape.Graham

[martin]

Hi Tony, you're heading in the right direction, just to review things, did you drain the block through the plugs on either side ? did you drain down and then refill with the heater fully on ? Fill VERY slowly, preferably with the front of the car higher than the rear, start the engine with the rad filler off and top up as it drops, when full, put the top back up and go for a run. when hot, does the engine "smell" hot ? does the engine make ticking and crackling noises as it cools after you've switched off ? If no to the last two then it's not overheating. With no stat, you don't know how hard the hoses get. Three quarters up the gauge is not a problem, you could easily have a faulty sender, new or not. I have a feeling you've been attacked by Stag paranoia, we all get it. Let us know how you get on. Martin.

[WealdenManinKent]

Hi Tony
As above, I always try to top-up the car with the front end raised on a slope to avoid air locks.
You said the gauge went more or less straight to 3/4 mark, many have commented that these gauges (and oil pressure gauges if fitted) are not that accurate (mine reads just over half rock steady with a new thermostat (old one was stuck open), before that it barely got over 1/4 mark for me when hot, but your gauge may be mis-reading.
Alternativly and worth remembering is the Voltage stabiliser for the tempreture gauge, this should be giving a steady 10v, maybe worth checking first with a meter if you have one?
Stag paranoia does strike in these situations, you said the car was running ok before, just the stat and the header tank had been replaced, so if you had any other probs before then this would have reared its head before now.
Also some here have brought hand held IR Thermometer N92FX from maplin to check for accuracy.
If still same then post back on here and you will receive a deluge of more useful ideas. Most important dont let it get you down. I have found owning a Stag is a constant learning curve
Roger

[singapore stag]

Hi Tony, EXACTLY similar symptoms to what I had when I did the header tank mod. Airlock thats what it was....Fill up and do as Martin and "Staggard" suggested hopefully that should sort it. It also helped when I loosened the hose going to the heater ( bulkhead ) I could hear air hissing out.

sukh.

[elvimto]

Tony,
did you remove the radiator and have it flushed cleaned in a radiator shop ? I would have started with that then replaced the stat before spending any money on the other stuff that being said you pay for your learning one way or an other. Is your radiator clean and have you had the car for a while ? do you know the history of the car ? if not then I would still pull it and have it cleaned and tested. You can work your way through the rest of the problems as you go. I drilled a hole in the stat and put that at the 12 o'clock position i think about 3/16 this will help get air and the circulation going. Don't panic, if the car had no cooling problems prior to you working on it it won't now. Do a complete flush out of the system that should remove any crap in the waterways and block just take your time and go through the system. Let us know how you progress.

cheers Stuart

[tony750cc]

Thanks for alll the suggestions, im thinking air, i didnt have it raised when i refillled the system. I drained it via the bottom hose and then where i removed the temp sender that drained the one block, i didnt think to do the other. i filled via the header tank only as it doesnt now have the rad plug with the new header tank, it seemed to take a lot of water. i added the flush to it as my intention was to run it up to temp then drain it and refil with clean (pink) anti freeze and water.
It wasnt sounding like it was overheating that much but the pressure was scaring me as the top hose was really hard. I hadnt fluhsed the rad as i was hoping by running a flush through it myself i could clean it before refilling it.
I have a steep drive at my house so maybe will try filling it on a slope. my temptation is to remove the stat again as thats how it was running before to see what its like. But im a bit wary of running it without one as im not sure if it will effect it much, guess its worth a try.
Will update tomorrow after ive had another chance to work on it!
Thanks for suggestions!

[martin]

Hi Tony, check that the stat has a hole or a jiggle pin at 12 o'clock as Stuart says, if not, drill one. do not run without it ! If yours is a Mk2 the pressure cap will blow off at 20psi, that's nowhere near high enough to do any damage. Drain the block at the drain plugs, the temp gauge won't have let much out, this is really only a one off so worth the little extra trouble. Martin. PS Roger, capilliary oil and temp gauges are accurate !

[Kevin Garrod]

I don't understand why anyone would remove the stat in an attempt to cure/hide an overheating problem. Correct me if I'm wrong but the purpose of the stat is to bypass the rad when cold to speed up warm up, once up to temp to continue bypassing the rad can only make things worse.

[V Mad]

If you have used the pink antifreeze, you need to be aware that some of these OAT chemicals are not compatible with the old ehtylene glycol types. At worst they can form a gel which blocks up the cooling passages. Hopefully yours is OK.

[Stagdad]

Hi Tony, EXACTLY similar symptoms to what I had when I did the header tank mod. Airlock thats what it was....Fill up and do as Martin and "Staggard" suggested hopefully that should sort it. It also helped when I loosened the hose going to the heater ( bulkhead ) I could hear air hissing out.

sukh.

I dont understand that Sukh ,the whole point of a header tank is that it self purges with a high part of the system venting off to the tank .If it gets airlocked there must be dip in the vent or it goes downhill somewhere.I think like you say the heater is where it can get trapped but that wouldn't be due to fitting the header tank.

Cheers Steve

[singapore stag]

I don't understand why anyone would remove the stat in an attempt to cure/hide an overheating problem. Correct me if I'm wrong but the purpose of the stat is to bypass the rad when cold to speed up warm up, once up to temp to continue bypassing the rad can only make things worse.

When the thermostat is closed, cold engine, the cooling water circulates through the by-pass without going through the radiator to speed up engine warming.

When the thermostat is fully open,no water flows through the by-pass and all the water flows through the radiator.

With no thermostat fitted, at all times you have water flowing through the radiator and at the same time the by-pass. So you have a % of hot water leaving the engine and going straight back into the water pump cover uncooled at all times. Not good.

Thus you must never run a stag without a thermostat.

With no thermostat it will take longer to reach normal running temperature.

Once you reach normal running temperature you have reduced cooling because hot water can still by-pass back into the engine.

So short runs would be okay until you reach normal running temperature...which take longer...then long runs could be problem...

Sukh.

The above explanation Coutesy of MJheathcote.

[Staggard]

I don't understand why anyone would remove the stat in an attempt to cure/hide an overheating problem. Correct me if I'm wrong but the purpose of the stat is to bypass the rad when cold to speed up warm up, once up to temp to continue bypassing the rad can only make things worse.

The thermostat stops the circulation through the rad when its closed it will only circulate through the heater if the valve is open, as the coolant in the block heats up the thermostat opens thus allowing coolant to flow from the block through the rad the more it opens the greater the flow. so removing the stat allows coolant to flow unrestricted. Graham

[Kevin Garrod]

Yep that's exactly what I understood to be the case and better put.

[Kevin Garrod]

My above response is to Sukhs post, should have used quote.