WTD - Bigger 404 exhaust
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  1. #1
    Fellow Frogger! Binky's Avatar
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    Default WTD - Bigger 404 exhaust

    Since fitting the 2 litre engine to my 404 (Binky), the engine has been overheating, it has been burning oil, and the water keeps boiling its way out of the radiator.

    I'm guessing that the cause of this is an overly restrictive exhaust system, as the symptoms are identical to those suffered when I got a kink in the exhaust system when I was running the original 1600 engine.

    I have a 2 litre manifold, but before I fork out for a new custom exhaust, I just thought I'd ask if anyone here has a system that might suit.

    Any leads appreciated...



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    Binky.
    Last edited by Binky; 21st July 2011 at 12:43 AM. Reason: Grammar

  2. #2
    Fellow Frogger!
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    It may be in your best interest to fork out for the new exhaust Just a straight-through 2.25" pipe with a single muffler at the end.

    But before you do that, are you sure the head gasket in not leaking exhaust gases into the radiator?

  3. #3
    1000+ Posts Beano's Avatar
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    There was a kink in the exhaust when it happened previously, but what might be restricting it now ?
    If you can't find a problem with the muffler, then I too suggest that the overheating is due to something else. Test yer thermostat, mate.....or take it out temporarily.
    Did you separate water pump and head ? If not, it is possible that the welsh plug behind the water pump is dislodged and you're not getting correct water flow. That would cause overheating. It's a common thing.
    Last edited by Beano; 21st July 2011 at 12:52 AM.

  4. #4
    Fellow Frogger! Binky's Avatar
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    Hi Thanos,

    I can't say that I have the utmost confidence in this engine, but it seems pretty good. It *may* be leaking exhaust gas into the radiator - anything is possible - but (given its performance in the 504 before I removed it) it is highly unlikely. Hence my thinking a new (bigger) exhaust is in order...

    Beano,

    The kink in the exhaust was on the original 1600 engine. I've since installed a 504 2 litre engine, but kept the original 1600 exhaust. It is an early 404 (1964) and has the poorly flowing manifold with the coffee tin resonator hanging off the front. Whoever replaced the exhaust before I had it seems to have thought that going down a size at each join was a good way to go. Thus the exhaust gets smaller and smaller...




    Binky.

  5. #5
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    I know the standard 404 radiators do a great job but did you transplant the 504 radiator at the same time as the motor?

    And those old pug radiators did greatly appreciate a good flush.

    Looking at some of the things mentioned might be worthwhile before paying someone to make a new exhaust.

    I also recall that 504s were a suseptible to head warpage if they overheated only a little. Even if a restricted radiator is the cause of the problem you might want to check that it hasn't triggered some other issues.

    P

    Oh, check the radiator cap, too.
    Daily Drivers: R10, R12, R17T(?) Decouvrable

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  6. #6
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Binky View Post
    Since fitting the 2 litre engine to my 404 (Binky), the engine has been overheating, it has been burning oil, and the water keeps boiling its way out of the radiator.

    I'm guessing that the cause of this is an overly restrictive exhaust system, as the symptoms are identical to those suffered when I got a kink in the exhaust system when I was running the original 1600 engine.

    I have a 2 litre manifold, but before I fork out for a new custom exhaust, I just thought I'd ask if anyone here has a system that might suit.

    Any leads appreciated...





    Binky.
    Check the 404 radiator is absolutely clean. The only way to this is to have a tank removed and to rod the tubes.

    A standard 404 radiator will just cope with a 2l engine. In traffic they can a bit hot.

    I've always fitted a 505 GR radiator as a precaution. I'm told VL radiators will shoe horn in as well.

    I don't want to be doom-sayer, but I doubt if it is an exhaust restriction causing overheating.

    Have you checked the pressure plug at the rear of the water pump in the head ? Is the fan clutch locked or fitted with a correctly placed and wired temperature switch ?

  7. #7
    Fellow Frogger! Binky's Avatar
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    Thanks for all the replies people

    I now realise I should have included some extra info...

    Yes, I fitted the 504 radiator at the same time as fitting the engine. I also installed an electric radiator fan, and removed the old fan hanging off the water pump. I removed the water pump and got the guy who machined the flywheel to remove unnecessary weight from the water pump pulley. At that time (Feb), there was nothing wrong with the welsh plug in the head behind the water pump, and the engine behaved fine in the 504 prior to removal. The issue didn't develop, it was there immediately, and aside from a more efficient fan, the only real difference I can think of is the more restrictive 404 exhaust system...

    Hence my wanted ad...



    Binky.

  8. #8
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Binky View Post
    Thanks for all the replies people

    I now realise I should have included some extra info...

    Yes, I fitted the 504 radiator at the same time as fitting the engine. I also installed an electric radiator fan, and removed the old fan hanging off the water pump. I removed the water pump and got the guy who machined the flywheel to remove unnecessary weight from the water pump pulley. At that time (Feb), there was nothing wrong with the welsh plug in the head behind the water pump, and the engine behaved fine in the 504 prior to removal. The issue didn't develop, it was there immediately, and aside from a more efficient fan, the only real difference I can think of is the more restrictive 404 exhaust system...

    Hence my wanted ad...



    Binky.
    Check the ignition timing
    Check the electric fan runs (short the temperature switch)
    Fan is "pushing" air if in front or "drawing" air if behind radiator, blades are in correct orientation
    Hoses in good condition and not collapsing.
    Radiator is unblocked inside and in the fins
    You are using premium unleaded

    Did you fit the 404 temperature sender for temperature gauge
    I'm not sure the 504/505 senders are the same resistance curve.
    It is fitted in the LHS rear of the head and not in the water pump

    May be worth trying an aftermarket temperature gauge. All my 404/504s have run at a maximum of 85 C about 180 F and spot on 80c, 176F after the fan comes in.

    I assume you have a 404 sump and not the 505 alloy sump? The 404 sump reduces the oil capacity and is less exposed to ram air flow therefore needs more radiator cooling.

    I always try to use an alloy 505 sump which fit in a 404, this is the best of capacity and cooling. The steel 504 sumps won't fit in 404: they have cross member gridlock.

  9. #9
    Fellow Frogger! Binky's Avatar
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    Wow Rob, that was quick!!

    Timing seems fine.
    Fan definitely works, is in front of the radiator (tight fit but managed to find one slim enough) and is running in the correct direction.
    Hoses are good.
    Radiator worked fine with same engine in the 504 prior to removal (so assuming it's still good).
    I only ever use 98 octane fuel (and yes, I use Flashlube or similar)

    I used the temperature sender from the 504 radiator for the fan.

    "May be worth trying an aftermarket temperature gauge. All my 404/504s have run at a maximum of 85 C about 180 F and spot on 80c, 176F after the fan comes in."

    According to the 404 temp gauge, your figures are spot on with mine. Fan kicks in at same temp, et cetera...

    No, I kept the 504 sump. Just had to bend the seamed edge a little to clear the engine mounts/crossmember. Before you say "there's your problem" there is no oil leaking - anywhere. Externals of engine, gearbox and diff are dry as a bone...



    Binky.

  10. #10
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Binky View Post
    Wow Rob, that was quick!!

    Timing seems fine.
    Fan definitely works, is in front of the radiator (tight fit but managed to find one slim enough) and is running in the correct direction.
    Hoses are good.
    Radiator worked fine with same engine in the 504 prior to removal (so assuming it's still good).
    I only ever use 98 octane fuel (and yes, I use Flashlube or similar)

    I used the temperature sender from the 504 radiator for the fan.

    "May be worth trying an aftermarket temperature gauge. All my 404/504s have run at a maximum of 85 C about 180 F and spot on 80c, 176F after the fan comes in."

    According to the 404 temp gauge, your figures are spot on with mine. Fan kicks in at same temp, et cetera...

    No, I kept the 504 sump. Just had to bend the seamed edge a little to clear the engine mounts/crossmember. Before you say "there's your problem" there is no oil leaking - anywhere. Externals of engine, gearbox and diff are dry as a bone...



    Binky.
    Did you remove the 504 temperature sender, ie the the thermistor that drives temperature gauge and replace it with the the 404 unit? Are you sure your temperature gauge is accurate?

    I've never attempted or eluded to be able fix the problem. Apologies if I'm repetitive or boring.

    I'm simply passing on a few years experience and a few years mistakes.

  11. #11
    Fellow Frogger! Binky's Avatar
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    Quote Originally Posted by robmac View Post
    Did you remove the 504 temperature sender, ie the the thermistor that drives temperature gauge and replace it with the the 404 unit? Are you sure your temperature gauge is accurate?

    I've never attempted or eluded to be able fix the problem. Apologies if I'm repetitive or boring.

    I'm simply passing on a few years experience and a few years mistakes.
    Hey Rob,

    To be honest I can't remember (i'm pretty sure I didn't though), I'll have to check my wiring tomorrow...

    I DO know that the electrical thermostatic fan is hooked up to the temperature sensor in the (504) radiator, and that the numbers you quoted match the numbers I get on the gauge in the instrument binnacle. After 47 years though, I'm sure that the gauge could be out.

    However measurements aside, the symptoms remain. And as I said, the only time I have previously experienced this particular combination of symptoms it was caused by one thing; a restricted exhaust...

    BTW. You're not repetitive or boring. You are methodical (and rightly so). Experience is 9/10ths of playing with cars! I'm one of the few younger sorts who like to play with the older things so I expect at some stage I'll be in your position, helping even younger ones with their pride and joy. So all help appreciated




    Binky.

  12. #12
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Binky View Post
    Hey Rob,

    To be honest I can't remember (i'm pretty sure I didn't though), I'll have to check my wiring tomorrow...

    I DO know that the electrical thermostatic fan is hooked up to the temperature sensor in the (504) radiator, and that the numbers you quoted match the numbers I get on the gauge in the instrument binnacle. After 47 years though, I'm sure that the gauge could be out.

    However measurements aside, the symptoms remain. And as I said, the only time I have previously experienced this particular combination of symptoms it was caused by one thing; a restricted exhaust...

    BTW. You're not repetitive or boring. You are methodical (and rightly so). Experience is 9/10ths of playing with cars! I'm one of the few younger sorts who like to play with the older things so I expect at some stage I'll be in your position, helping even younger ones with their pride and joy. So all help appreciated




    Binky.
    I'm not entirely sure the temperature senders in head are the same for 504/404, so you may just have a temperature gauge that is reading high. The engine may be running at the correct temperature in fact.

    Can you temporarily disconnect rear/ middle muffler and take the car for a "blast" ?

  13. #13
    1000+ Posts jo proffi's Avatar
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    So, you suspect your exhaust is restrictive.
    Have you measured the pressure???

    guess-a-metrics is an expensive game, so best to measure the pressure and know for sure.

    http://autospeed.com.au/cms/title_Fr...5/article.html


    The above link goes in to detail how it is done.
    I measured mine this way. Apart from the pulse which you cant read with any accuracy off an analogue gauge you should get a reading that will confirm or deny your idea that the exhaust is a restriction.

    Jo

  14. #14
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by jo proffi View Post
    So, you suspect your exhaust is restrictive.
    Have you measured the pressure???

    guess-a-metrics is an expensive game, so best to measure the pressure and know for sure.

    http://autospeed.com.au/cms/title_Fr...5/article.html


    The above link goes in to detail how it is done.
    I measured mine this way. Apart from the pulse which you cant read with any accuracy off an analogue gauge you should get a reading that will confirm or deny your idea that the exhaust is a restriction.

    Jo
    What's normal back pressure, Jo?

    The examples the given in the article are hardly representative of a 60s designed, side cam 4 cylinder with triple muffler system and no CAT, fuelled by a twin choke carby.

    If the reading were 3 of 5 times what is stated, the yes there is problem.

    It's an interesting article anyway.

  15. #15
    1000+ Posts jo proffi's Avatar
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    I dont know Rob, but you should get an idea by observing the pressure through the rev range.


    The article suggest the upper limit is around 13 psi, so using that as a guide, a picture should be fairly easy to form by connecting the gauge and taking the motor to redline.

    IF nothing else, it will give a before and after reading if exhaust work is initiated.

    Jo

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