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HT4100 4.1, 4.5, 4.9 Discussion, Is 104C too hot for a 4.9L 1994 Deville? in Cadillac Engine Technical Discussion; About the backfeed into the circuit I have installed an extra relay. This job has been completly done by an ...
  1. #16
    tomtom is offline Cadillac Owners Member
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    About the backfeed into the circuit I have installed an extra relay. This job has been completly done by an car electrical service (Bosch).

    The adujustable temp control switch from Jeg's seems to bee the more confortable solution. I first have been looking for something like that in Germany, but nothing could be offered from BOSCH service.

  2. #17
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    bosch service ???

    i suppose they came about to service there fuel injection systems over there years ago ?

    I spent 45 minutes in frankfurt ..not long enought to see or learn anything ...

  3. #18
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    You don't want to trigger the fans to compete with the thermostat temp though, if the stat is a 92C stat (195 F) and the fans are trying to cool to 180 (like many aftermarket ones do that are intended for a cooler thermostat), it will never shut off. I am pretty sure GM triggers the fans late for fuel economy reasons (less electrical load), and possibly some improved emissions (that remains to be proven....). (BBob, can you confirm?)

    But no, I don't like any car to run over 210F.

    Maybe this is a great time for synthetic eh? (just kidding!!!)

  4. #19
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Quote Originally Posted by tomtom
    There are two ways to keep the temperature on a 90°C level. An expensive one and a cheap one. I selected the cheap one : I installed an extra circuit on my dashboard. Everytime I have to stop in drive for longer time and the temperature exceeds 100°C I turn on the blower by hand.
    The expensive way is to installe an extra thermostat ( you can get them for older English cars like Austen Healey ) that starts the blower automaticily on 95°C.
    What do you mean by the blower? The coolant fans? Thats the way they designed these engines. I would say after extensive testing they figured this was the best tem that the engine could run at. Sitting at idle my 90 seville with the PFI 4.5 wont kick the fans on till it says 222 F on the info panel. At 233 F the fans go into high mode. My car has been this way since it was new and it now has 224,800 miles with nothing done to the engine but a waterpump. If you are having headgaskets problems then I would imagine the 10 degree difference is just masking the problem. I would suspect a surface irregularity in the head or block which is causing the headgasket to leak. I have had no problems and I have never used any of that coolant supplement crap either. But I change my antifreeze every spring, so that probably makes up the difference. I did notice that with the A/C on my seville on a hot day, like 90 degrees, will climb to 233. The fans go into high mode and it cools right down. Out on the highway without the air running it will run 198-205. A 195 degree thermostat is not fully open until 210 degrees. It starts to open at 195. Some people are mislead by that. However, I think that 220 should be normal. If it gets past 222 F while out on the highway, then I would suspect a thermostat not opening all the way. I sure wouldnt want to violate the vehicle electronics by adding a fan switch or thermo.

    Blaze

  5. #20
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Forgot to add that if this was a bad set-up then why has my car lasted this long? A lot of people I see have accumulated thousands of carefree miles without problems.

    Blaze

  6. #21
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    220 degrees F coolant temp has absolutely no ill effect on the engine or the head gaskets. Geez...as much as these systems are tested you would think that someone might recognize an issue with the coolant getting above 90 degrees C....LOL LOL.

    There is absolutely no reason in the world to try and keep the coolant temp at 90 degrees C.

    If the system is operating correctly with a working 14 PSI pressure cap and a fresh mix of 50/50 coolant/distilled water the system will be in complete control and will not boil over until the coolant temp gets to 128 C or 265 F. The engine can actually operate at temperatures above that point with no problem so the engine nor the head gaskets nor anything else will be damaged until the temp exceeds 265 and the system boils dry and then gets much hotter.

    If head gaskets fail in an engine it is due to other problems then the coolant temperature getting above 90 C....

    There are millions and millions of 4.1/4.5/4.9 engines and Northstars running around perfectly fine with the cooling fans not even activating until the coolant gets to 225 F....that is perfectly normal and if damage were occurring then they would all be loosing head gaskets right and left. They don't.....

  7. #22
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Thanks guys for the info. I appreciate it. Thanks Again.

  8. #23
    pink panther is offline Cadillac Owners Member
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    I am new to Caddies and their design quirks.

    Please explain the annual coolant change and "GM coolant supplement" ??



    Is the supplement item pricey?? or reasonable??

    Any generic products work - or not worth the risk??

    Thanks in advance

  9. #24
    peteski is offline Cadillac Owners Enthusiast
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Lets not go through this again.. Pink, search this forum for "coolant supplement" or "Bars leak" and you'll have abut a week's worth of reading!

    You'll be an expert!
    Peteski

  10. #25
    89eldorado is offline Cadillac Owners Fanatic
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    The service manual speaks of drain plugs in the block. Do they mean the freeze plugs? Are you really supposed to remove those to do a complete flush?

    Thanks,
    Brian <long time since I posted>

  11. #26
    pink panther is offline Cadillac Owners Member
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Thanks for the suggestion of the forum

    Sometimes some of us forget all the extra areas on this site.

  12. #27
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Quote Originally Posted by 89eldorado
    The service manual speaks of drain plugs in the block. Do they mean the freeze plugs? Are you really supposed to remove those to do a complete flush?

    Thanks,
    Brian <long time since I posted>

    The drain plugs mentioned are not the freeze plugs.

    There is really no need to remove the drain plugs. Just use compressed air or the output of the shop vac to push as much of the coolant out of the block as possible and refill with fresh 50/50.

  13. #28
    bwood is offline Cadillac Owners Member
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Quote Originally Posted by bbob
    220 degrees F coolant temp has absolutely no ill effect on the engine or the head gaskets. Geez...as much as these systems are tested you would think that someone might recognize an issue with the coolant getting above 90 degrees C....LOL LOL.

    There is absolutely no reason in the world to try and keep the coolant temp at 90 degrees C.

    If the system is operating correctly with a working 14 PSI pressure cap and a fresh mix of 50/50 coolant/distilled water the system will be in complete control and will not boil over until the coolant temp gets to 128 C or 265 F. The engine can actually operate at temperatures above that point with no problem so the engine nor the head gaskets nor anything else will be damaged until the temp exceeds 265 and the system boils dry and then gets much hotter.

    If head gaskets fail in an engine it is due to other problems then the coolant temperature getting above 90 C....

    There are millions and millions of 4.1/4.5/4.9 engines and Northstars running around perfectly fine with the cooling fans not even activating until the coolant gets to 225 F....that is perfectly normal and if damage were occurring then they would all be loosing head gaskets right and left. They don't.....
    did you guys put the iron heads on
    for durability or to hold more of this
    heat in the combustion chamber???

  14. #29
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    The iron heads were a design consideration to minimize costs and maximize durability. Remember that the engine was designed back in the late 70's and early 80's and started production in early 1981 as an 82 model. Back then aluminum cylinder heads were not that common, especially on high volume engines. The weight of the cast iron in the heads was minimized by making the heads very small in cross section...from the end they look triangular nor rectangular. From an end view the part of the head that is the intake ports is made up by the aluminum of the intake manifold.

    The major mass in the engine, the block, was made of aluminum to maximize the mass savings by using the premium material.

    Aluminum heads require that the valve seats be machined out and steel valve seat inserts by pressed into place. In those days this was still a bit tricky for a high volume engine. The cast iron head allows induction hardened valve seats machined directly into the parent cast iron of the cylinder head which is very very durable and very cost effective. Keeping the ability to make the valve seats out of the cast iron of the head adds to the cost effectiveness and the durability of the head and the minimized cross section of the head keeps the mass down by minimizing the amount of cast iron.

    It had nothing to do with heat or retaining heat or anything else. Cast iron heads are very durable and excellent parts. The only reason for aluminum heads is for mass reduction. In a DOHC engine like the Northstar the heads are quite large so the mass penalty of making them out of cast iron would be severe so aluminum is used.
    Sevillian273 and Sevillian273 like this.

  15. #30
    tony1963 is offline Cadillac Owners Member
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    Re: Is 104C too hot for a 4.9L 1994 Deville?

    Some guy with a can of beer in one hand and a remote control in the other knows more than the engineer who designed the engine.

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