505 overheating
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Thread: 505 overheating

  1. #1
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    Icon9 505 overheating

    Have just finished restoring the cooling system on my GR and it seems to be overheating.
    Temperature gauge reaches 3/4 and rain dropping on the bonnet yesterday was turning to steam.
    The cooling was perfect prior to my intervention.

    The initial problem:
    Coolant level always dropping even before visible external leak appeared.
    Water pump outlet pipe to heater was badly corroded and leaking so the
    pump was replaced.
    Found the welsh plug had popped out and fixed itself parallel to the impeller and was hitting the impeller lightly.

    The solution:
    Screwed in a new welsh plug.
    Replaced the water pump.
    Fitted brand new thermostat which I tested first in a saucepan.
    Using near fan hub and pulley from my other GR I endeavoured to set up the electromagnetic fan to work as Peugeot intended.
    Setup with 0.3 mm gap for it to move freely.
    Removed crossflow radiator which seemed to be in good order in the first place and reversed flushed with garden hose.
    Put all back together and set belt tension as specified and filled with coolant.
    Opened bleed screw on hose to carby as specified and tightened once filled.
    Not able to drain block as specified as the drain plug does not seem to be where it should be located in the Haynes manual.

    What happens now:
    The fan engages immediately from a cold start and not later as it had been designed. Though the carbon brush, temp. sender are all wired up.
    Temperature gauge quickly reaches 1/2 way point and if stuck in traffic it goes to 3/4 but not beyond to the red line, so far.
    After stopping for half an hour the radiator cap is still under some pressure and it flies about a foot into the air.

    Thought I had done a great job as there were no leaks to overcome.
    However initial results indicate that something may be wrong.

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    Any suggestions on any of the above?

    _________________________________________________

    Peter 505 '83 GR

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    Banned orestes's Avatar
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    might be completely out of whack here, but recently before the head gasket blew on the srdt, it was overheating to half way to 3/4. caused a lot of other problems as well though, i.e burst hoses and cracked the radiator

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    Quote Originally Posted by orestes
    might be completely out of whack here, but recently before the head gasket blew on the srdt, it was overheating to half way to 3/4. caused a lot of other problems as well though, i.e burst hoses and cracked the radiator
    Well I certainly do hope that you are completely out of whack there.

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    Banned orestes's Avatar
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    so do i

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    Budding Architect ???? pugrambo's Avatar
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    when you turn the ignition on can you turn the engine fan ?

    now then with the car running and the cap off can you see any bubbles and is the coolant a slightly brown colour ?
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    Well once the ignition is turned on the fan is travelling at mach speed, but I did experiment by jamming it before starting and the pulley rotates freely. When the fan is released it is flying again.
    The fan hub is free of the pulley magnet but chooses to be engaged upon starting.

    There are no bubbles or discolourisation of the coolant.

  7. #7
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by PUG_504_505
    Well once the ignition is turned on the fan is travelling at mach speed, but I did experiment by jamming it before starting and the pulley rotates freely. When the fan is released it is flying again.
    The fan hub is free of the pulley magnet but chooses to be engaged upon starting.

    There are no bubbles or discolourisation of the coolant.

    sounds like you have a hub that is dead
    you need to check that it isn't earthing or the windings in the hub are ok

    but you may also have a switch that is dead in the radiator and maybe worth checking

    check the sender first then look further

    are you losing any coolant ?

    start the car and remove the oil filler and check for steam when the engine is hot as this is a sure sign that you have liner seals on their way out

    be sure it is steam and not oil vapour though

    is there any mayonaise in the oil filler at all ?
    3 x '78 604 SL

    1 x 2018 3008

    1 x 2000 Citroen XM,

    1 x '98 306 GTi6 sadly sold

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0

  8. #8
    Moderator Alan S's Avatar
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    The symptoms are those of air in the system.
    What happens in those cases is that the engine gets red hot but the fans will not be rotating due to air being around the fan sender unit instead of water as a result it doesn't sense the heat & won't start the fan, (although I must admit I don't know how the Pug system works but you mention a thermal switch).
    To top up & remove the air on Cits & on some Renaults, they make a funnel & jam it in the filler hole with an extension a foot or so above radiator level, Fill to the top, bleed system, close bleeders & leave sit for a while with the engine running. Switch off & let cool and see if the level drops as coolant replaces air.
    Another point that I always make (I don't know how many ever check it) is that if the fan has an electric motor on it, be sure the rotation is right. That is one of the biggest traps I've ever seen owners fall for. (But I don't think that's an issue on a 505 is it?)
    Blown gaskets incidentally, usually end up blowing the cap halfway to mars although air turning to steam can create some stellar pressures also.

    Alan S
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  9. #9
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    For pugrambo

    The hub and pulley should be okay as they are new parts ( totalling $450! ).

    The sender is old but how do you test it for any life? ( Resistance or voltage measurement? )

    Not losing any coolant.

    No steam from the oil filler.

    Oil in the oil filler is not contaminated, good as gold.


    For Alan S

    The 505 does not use an electric fan but an electromagnet arrangement.

    An air lock could be an issue as while there was a bleeding screw hanging off the carby for coolant I was not able to locate a drain plug on the block itself.

    Initially following the first run after filling the coolant level did drop so I interpreted that as the air lock having been replaced.

    The level no longer drops but perhaps there is still air in there somewhere?

  10. #10
    Moderator Alan S's Avatar
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    Air can be the biggest bugbear when it comes to proper operation you can imagine.
    I'll give you two examples of how awkward it can be to get out & how easy to get it in.
    Case #1:- We fitted a 2500GTi mechanicals to a 2400 CX Citroen. All went well until we were about 3 klms from home when it erupted like a steam kettle. Hoses blown up like balloons, steam coming from around all the connections. Let cool down & drive home. When we get home; same drive over the same distance, it's running normally. We check all the bleeder valves & all check out OK. Next day we go out again & at exactly teh same spot, it again boils. We let it cool and then slacken bleeders and use hoses like pumps by squeezing them until all bubbles disappear. We drive it for a couple of days, all seems well; then it does it again.
    Eventually we discover 2 causes. First was that the engine in a 25GTi sits at a different height to a 2400 as a result, unless the header tank is filled to overflowing, air gets trapped in the top of the heater. Second cause was that we had a slight leak at the intake hose to the pump. These don't leak when the car is running but rather when it is stopped due to them being on the intake side of the pump. The water leaks out under pressure and as it cools, it sucks air into the system.So we fixed the leak, used a funnel in the header tank when filling...problem was then solved.
    Case #2:- After doing a cylinder head rebuild on another CX that we bought with a blown head gasket, we restarted it all confident everything was as new. It ran quiet & smooth just as we had hoped. After about 12 minutes, the temperature gauge (an extra that had been fitted by the previous owner) started to rise rapidly and once it started there was no stopping it. It went through the roof & the car boiled like a Stanley steamer.
    Cause; the sender unit had been installed in the same fitting that had originally housed the sensor for the temperature light, but in this case it was physically larger. As a result, it acted like some kind of diverter valve & for some reason when this mongrel gauge was in the system, it was impossible to get the air out. Removed the gauge, refitted the light and the problem was solved.
    I know this is a long winded rant that may seem to be about nothing, but the point I am making is that when it comes to purging the air out of these pressurised systems, there is absolutely no room for error nor can compromises be made.
    As a side issue, I had a combustion stove connected to a hot water system & someone had supplied a faulty designed tank that according to a workplace health & safety officer who was up on tanks, pressure systems & steam that the pressure generated by an airlock due to it converting to steam within the system was powerful enough to kill everyone within a 30 metre radius had the tank blown. Armed with that information, it's not hard to understand how a cooling system will totally block off if contaminated with air & that air, mixed with water becomes steam.

    Alan S

    P.S. I had figured out about the fan system hence my comments to that effect.
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  11. #11
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    I'll go with you on the air thing Alan> I had the same problems with a 604 of mine. The radiator cap leaked air on suction not pressure. Consequently at highway speed the system sucked in air as the water flow going past the cap base acted like a ventury. Took me ages to work out the problem.
    Wasn't until I got another one (604 ) that didn't get hot or find air that I was able to work it out.

    Reply to question how to test the sensor, use hot water on the stove and a light globe wired throught the sensor. When the temp reaches the right level the light globe should light up to show that at that temp your thermo fan will engage.

    The thermo fans will still spin very fast even when they are not engaged.
    If it is really engaged it will trully suck some air if you give the motor a rev.

    If all is normal then the temp sender unit may be dodgy.

  12. #12
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by Warren Gordon
    I'll go with you on the air thing Alan> I had the same problems with a 604 of mine. The radiator cap leaked air on suction not pressure. Consequently at highway speed the system sucked in air as the water flow going past the cap base acted like a ventury. Took me ages to work out the problem.
    Wasn't until I got another one (604 ) that didn't get hot or find air that I was able to work it out.

    Reply to question how to test the sensor, use hot water on the stove and a light globe wired throught the sensor. When the temp reaches the right level the light globe should light up to show that at that temp your thermo fan will engage.

    The thermo fans will still spin very fast even when they are not engaged.
    If it is really engaged it will trully suck some air if you give the motor a rev.

    If all is normal then the temp sender unit may be dodgy.

    also with the 604 you have that top hose that sits above the radiator............what a great idea that is

    i use a funnel whenever i need to do any topping up on them which reminds me i really do have to stick some new coolant in the car........and service the tranny..........and get a wheel alignment..........and change the oil in both cars............and mow the lawn...........and clean up some more engine parts...........and whatever else the missus needs me to do after all that
    3 x '78 604 SL

    1 x 2018 3008

    1 x 2000 Citroen XM,

    1 x '98 306 GTi6 sadly sold

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0

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