405 running a hot temper
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  1. #1
    Member anhtu's Avatar
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    Default 405 running a hot temper

    Hi All,

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    My 405 heating saga continues: I need some advice about a heating problem (at least I think it is a heating problem) I am having.
    Here's the description:
    After replacing the thermostat, I noticed that the engine still heats up too rapidly. The fans kicks in at about 95C on the gauge, and the temperature then drops for a short while, before it rises again pass 100C and I noticed that the engine then looses power (tach intermittently drops about 2000 rev for a split sec or two) and the gauge keeps climbing pass 110C - that's where I said enough, pull over and turn the car off. Then it would not start until the engines have been cooled for at least 2-3 hours. There is no loss of coolant though with a radiator check. I'm puzzled.
    Starting the car after the 2-3 hour cool down period, I noticed the stuttering power loss problem happening at a much earlier temperature range (90-100C) with the same rate of heat build up as before.
    Has anyone seen this problem before? I would appreciate some advice or tips as to where to start looking for answers. The 405 is a Oct90 sedan model fuel injected 1.9L petrol.
    I miss my 504!! She was low maintainance compared to this young hot head. :-)

    thanks in advance.
    anhtu
    Last edited by anhtu; 24th July 2005 at 01:58 AM.

  2. #2
    Fellow Frogger! Decca's Avatar
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    Anhtu

    I take it the thermostat is in the correct way, with the bulb/spring part into the block.

    Does the car run ok before it overheats? as timing too far advanced can cause overheating
    If the pump was stuffed warm up time would be normal as the thermostat blocks circulation till coolant is hot. I wonder if there is air in the system .Or it may need a good flush.

    I am not familiar with 91 mod 405 but check where the temp sensor is on the block . it may give a clue. It could be stuffed. pull it out, check there's coolant there. Using a multimeter, resistance drops as temp rises ( generally)

    As for the engine loosing power when she's very hot.. it may be a second fault.. or... as a safeguard the engine computer may shut down or rev limit the engine when a sensor goes into a danger zone.

    Decca
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    Past -- 19?? 403 / 1974 504GL / 1972 R12TL / 1995 405SRi / 1997 406ST / 1998 306XT / 2004 406HD1 / 2008 308XSE HDi / 2008 307XSE

  3. #3
    Fellow Frogger! nick86's Avatar
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    i had a bit of a cooling issue with my 405 too, im guessing the system is the same across all 405s...

    the stage one fans come one at 92 (the dial isnt too accurate thats from the book) and theyre not terribly fast, but they can keep it somewhat cool, if the car stays statinoary, the stage two fans should come on at 98, and those puppies are mean, they will drop it to 80 in no time, then the cycle starts again

    from what i can gather your stage two fan speed isnt activating, thats assuming of course that this is all while the car isnt moving, if you are overheating while air is passing through the radiator from the car rolling along nicely then i would suggest looking at the radiator itself

    best of luck
    '92 405 mi16

  4. #4
    Member anhtu's Avatar
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    Thanks Nick + Decca,

    I think the stage 2 fan could be the problem - it doesn't increase in speed at all.

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    Fellow Frogger! nick86's Avatar
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    Quote Originally Posted by anhtu
    Thanks Nick + Decca,

    I think the stage 2 fan could be the problem - it doesn't increase in speed at all.
    if u can tell the stage one fan is turning on then when stage two kicks in, you will really, really notice, lights dim and everything, its wicked

    so yeh if you cant tell its getting faster then id say thats the problem
    '92 405 mi16

  6. #6
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    when the stage two fan kicks how long does it stay on (when driving). I have noticed that i can hear a fan chip in like every 5 or so mins on my 94 405sr. also there is a 5-6degree variance between driving wih the a/c (runs hotter)on as opposed to driving with it off. I have driven other cars(japanese) and not seen this happening

  7. #7
    Fellow Frogger! Decca's Avatar
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    In my 94 SRI I hear my fans cut in and the guage goes down quite quickly and I'm possibly only hearing the stage 2 point when both fans get 12volts. in Stage 1 they only 6volts each as both fans are connected in series.

    So to answer your question ssmikle, The stage 2 fans are only on for a minute or so. I hear my cut in fairly regularly in city driving. I havent noticed any difference with the aircon but usually cars with aircon have bigger/more fans as the condenser generates heat

    Let the car idle whilst peering into the grille and check the stages cut in. The fans are controlled by three relays and a search on AF will drag up a circuit.
    I dont know if that is your problem. Does the car overheat if coasting along on a country road or a freeway as the fans are usually only needed when there is not enough airflow through the radiator


    Decca
    Present --2016 2008 Outdoor / 2014 RAV4 Diesel (My utilitarian beast)

    Past -- 19?? 403 / 1974 504GL / 1972 R12TL / 1995 405SRi / 1997 406ST / 1998 306XT / 2004 406HD1 / 2008 308XSE HDi / 2008 307XSE

  8. #8
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    The thing is i am not sure if it is a problem or if thats just the pug way. as i had stated i haven't seen that happen with any of my previous cars. in the pug while driving without the ac th temp is usually around 88/89. with the a/c on it may go up to about 92/93 depending on external temp, traffic or terrain. Is This normal for peugeots(my model)

  9. #9
    Fellow Frogger! JAG80's Avatar
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    Quote Originally Posted by ssmikle
    when the stage two fan kicks how long does it stay on (when driving). I have noticed that i can hear a fan chip in like every 5 or so mins on my 94 405sr. also there is a 5-6degree variance between driving wih the a/c (runs hotter)on as opposed to driving with it off. I have driven other cars(japanese) and not seen this happening

    My stage 2 fan rarely comes on. Only when the engine has overheated due to a cooling system problem, hot summer weather or if my a/c is on. My car actually runs cooler when the a/c is on because the stage 2 fan is activated when I turn it on. For normal driving the stage 1 fan is enough to keep the temp. down (think it kicks in at about 95) and if the second one comes on I start getting suspicious.
    Blood Orange 2006 Renault Megane Sport Cup
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  10. #10
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    Default 405 temp

    My mechanic says japanese cars etc use suppressors to keep the temp gauge at"safe', unalarming levels. They only go to max when boiling. French gauges however register across the whole range. In other words, you probably weren't getting a true reading from gauges on your other cars.

  11. #11
    Moderator Alan S's Avatar
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    Jap stuff is always a trap. How many Toyotas have cooked engines because they ran low on water and didn't read anything apart from normal because they only register upon contact with the actual coolant.
    The dreaded "Stop Immediately - Danger" red light usually comes on about 20 mintes after the engine has seized and the coolant eventually condenses and triggers the sensor.


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

  12. #12
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    Quote Originally Posted by kellyo
    My mechanic says japanese cars etc use suppressors to keep the temp gauge at"safe', unalarming levels. They only go to max when boiling. French gauges however register across the whole range. In other words, you probably weren't getting a true reading from gauges on your other cars.

    I hear you it will take some getting used though. Thanks. oh one point of correction. I had said that the car runs around 88-89degrees without the a/c on its actually 78-79 degrees then with the a/c it goes to about 88-89 but has gone to as high as 94-95. but you guys say its normal so i'll let it be

  13. #13
    Fellow Frogger! Roland's Avatar
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    Quote Originally Posted by anhtu
    Hi All,

    My 405 heating saga continues: I need some advice about a heating problem (at least I think it is a heating problem) I am having.
    Here's the description:
    After replacing the thermostat, I noticed that the engine still heats up too rapidly. The fans kicks in at about 95C on the gauge, and the temperature then drops for a short while, before it rises again pass 100C and I noticed that the engine then looses power (tach intermittently drops about 2000 rev for a split sec or two) and the gauge keeps climbing pass 110C - that's where I said enough, pull over and turn the car off. Then it would not start until the engines have been cooled for at least 2-3 hours. There is no loss of coolant though with a radiator check. I'm puzzled.
    Starting the car after the 2-3 hour cool down period, I noticed the stuttering power loss problem happening at a much earlier temperature range (90-100C) with the same rate of heat build up as before.
    Has anyone seen this problem before? I would appreciate some advice or tips as to where to start looking for answers. The 405 is a Oct90 sedan model fuel injected 1.9L petrol.
    I miss my 504!! She was low maintainance compared to this young hot head. :-)

    thanks in advance.
    anhtu
    Check the fundamental parts first.
    The most important part for keeping the engine at the correct temperature is THE RADIATOR.

    Remove it and get it tested/cleaned/replaced or whatever is neccessary. A new one for my Mi16 cost $462 through Natrad. (Plastic/Aluminium 50mm thick Valeo unit from France)

    Now you can be certain that the most important part is working.

    Then you check the thermostat (because that is designed to stop water flowing through the radiator).

    Once you have those 2 fundamental parts working correctly then overheating in traffic is likely to be cooling fans not cutting in.

    Good Luck

  14. #14
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    Hey Decca. the fans are tripping. If i am in traffics the temp may go up to about 90-92 but once i get clear and start freeway driving it goes down. I actually spoke to mechanic from bermuda who said it's running a bit cold so i should check the thermostat (should have done that a few weeks ago but the mechanic and just can't seem to hook up) i am doing some out of town driving this weekend so it looks like sometime next week

  15. #15
    Tadpole Psycho Budgie's Avatar
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    This may or may not be of any help but..........

    I had a major overheating problem in my 405 a couple of years back after getting stuck in a slow moving tailback. The temperature shot up and the radiator split. After fitting a new radiator and thermostatic switch the car was still getting hot.
    My mechanic and I tracked it down (after stripping off the front bumper) to a rotten bayonet connection in the fan wiring.
    About 3 months later he came across exactly the same overheating problem with exactly the same rotten connection on another 405.



    Like I said this may not be of any help to you, but hopefully it may help someone else catch the problem before they fork out for a new thermostatic switch or their radiator splits.

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