4.5L Valve Pinging / Clattering - Page 2
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HT4100 4.1, 4.5, 4.9 Discussion, 4.5L Valve Pinging / Clattering in Cadillac Engine Technical Discussion; Well....without being there, etc.....sounds like you are narrowing it down and the EGR valve would be the logical guess. You ...
  1. #16
    BeelzeBob's Avatar
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    Re: 4.5L Valve Pinging / Clattering

    Well....without being there, etc.....sounds like you are narrowing it down and the EGR valve would be the logical guess.

    You can make a simple tool to make the EGR easy to remove with a cheapie socket welded to a piece of scrap iron bent in a C shape. Make a C out of the strap iron about 2 inches X 6 inches X 4 inches. Weld the socket to the outside of the 2 inch leg of the C and it will let you reach right around the EGR valve hat to get to the bolts.

  2. #17
    bantar is offline Cadillac Owners Member
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    Re: 4.5L Valve Pinging / Clattering

    Adalla, I wouldn't think clean and inspect would help you with opening of the EGR. Last time I pulled mine, I pulled the throttle body to get at one bolt. Gonna have to get me a welder one of these days. However, if you do end up replacing yours, please let me know how it goes.

    Easily enough, I guess I can get a new one and connect it to the vacuum to see if it opens and closed properly without actually installing it. The issue at hand is failure to open.

  3. #18
    adalla is offline Cadillac Owners Fanatic
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    Re: 4.5L Valve Pinging / Clattering

    Welll... just put all together and... nothing changed!LOL The EGR valve was not that dirty. Removing it was a pain - had to remove TB. Good thing is that I cleand the TB really good and replaced all the hose connections with new pieces of vacuum rubber.

    CONCLUSION: EGR valve and the solenoid are not most likely the culprits.... I believe the sysrtem with age loses vacuum because of all dried out rubber, gaskets etc. I am absolutely positive the vacuum I have on the EGR valve input cannot drive it despite I know EGR valve does not need much since it has exhaust gas backpressure. Well... I'll have to disassemble whole thing again since i lost somewhere new EGR valve gasket and had to use old one... which may be NOT good either.

    Special thanks to GM engineer who designed the EGR valve! Just do not tell me they could not nake it a little bit higher so one could put a socket on it without removing TB all making a special tool. THAT's sucks. Sorry bbob this has nothing do to with bright GM engineers , but I believe you must have a special department to make DIY guyses life miserable! LOL

  4. #19
    adalla is offline Cadillac Owners Fanatic
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    Re: 4.5L Valve Pinging / Clattering

    BTW bypassing the solenoid makes difference - the knock goes away. The reason most likely is that the EGR valve gets enough vacuum to open. I am going tpo lay with bypassed vacuum hose to gigure ot the minimum vacuum which can open the valve. Another possibility is that the threshold og the EGR valve changes with age for number of reasons and to proparely operate it needs more vacuum.
    The knock is most pronounced when you power brake at 1200-1250 RPM. Actually i think I already killed my transmission chasing this knock. I powerbraked it 10 times in a row at 2000 RPM and the manual say you cannot do that even at 1000 RPM for more that 6 seconds! LOL In other place the same mabual says get stady 2000 RPM (powerbraking) to check the operation of the EGR system . How can you get stady 2000 in 6 seconds? LOL

  5. #20
    BeelzeBob's Avatar
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    Re: 4.5L Valve Pinging / Clattering

    I doubt that you hurt the trans. It can take a lot of brake torqueing if you restrict it to short intervals and allow it to cool off inbetween and keep the brake torque to a minimum throttle angle.

    The EGR valve is fairly complex inside. It is not just a simple vacuum diaphragm inside the can. There is a series of diaphragms inside that actually sense exhaust backpressure from the pintle, up the inside of the shaft into the valve operating head. That regulates the vacuum level inside the EGR valve. So....just applying vacuum to it does not signal that it is good or bad if it is off the engine and not in normal operation. If the valve is seeing good vacuum levels when the EGR solenoid opens and it is not moving or controlling then I would have to suspect the valve itself. They are pretty robust and rarely fail....but that doesn't mean they can't after enough time and miles and heat and such.....

    I'll take your criticism of the EGR valve packing with a large grain of salt. I have personally changed MANY of them and with the special wrench I mentioned it is very easy. Sorry you do not have one. EGR valves like that are very common on all GM engines for many many years so the valve was designed to be as short and compact as possible so as to fit onto as many applications without changing the design as possible. Considering that there were probably 10,000 or more of them manufactured every day at one point in time the design was pretty much driven by how it fit on all engines...not just the 4.1/4.5/4.9. Besides, how often do you REALLY need to remove the EGR valve. On a scale of 1 to 10 I would put it at about a 3 I guess because of the tight clearances. Otherwise it is pretty easy....just bend over and remove it. No need to crawl under the car or take 30 other things off or anything. For something that has to be removed once per 100K or usually never I wouldn't say it is something to criticise for servicability....LOL

  6. #21
    adalla is offline Cadillac Owners Fanatic
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    Re: 4.5L Valve Pinging / Clattering

    bbob,

    I understand that parts are made for several applications, there is need to save weight, etc., but serviceability seems to be not a priority IMHO. I bought the car five years ago with 77.000 miles and it already had that knck (may be less pronounced) so perhaps at that point the EGR valve already needed replacement. Who knows? LOL Of cousrse next time I'll do the job much faster since I know I have to remove TB so will not waste my time figuring out how I can remove EGR valve without disturbing TB!

    As far as the transmission is concerned ... unfortunately, I made some 10 powerbrakes at 2000 RPM in a row for 30-60 sec each The color of ATF a little bit brownish but it does not smell burnt. I dropped fresh ATF on the same napkin and it was much brighter and pink and smelled "brighter" as well (like kerosine to me). The ATF has been changed four years ago when the car made 100.000 miles. It is 143.000 right now.

  7. #22
    bantar is offline Cadillac Owners Member
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    Re: 4.5L Valve Pinging / Clattering

    I think I can safely say that my EGR valve did indeed cease to operate properly. It was one of those rare ones that failed closed. Although, I got about 175K miles on the part.

    I bought a new EGR valve and tried to "bench" test it with the engine vacuum and it did not work either, so I sat on this for a few weeks while pondering the next step. Purchased a vacuum guage and confirmed that I'm getting 10-14" hg depending on engine speed. I did put the car in drive and tested the solenoid at various engine speeds. It opened at speed and was closed at idle, so I was left suspecting the EGR valve again.

    I suspected that the egr valve needed backpressure to assist the vacuum and sure enough, after I opened the package with the instructions, it said clearly that the device could not be bench-tested. This very generic EGR valve came with about 50 different numbered and sized orifices which you had to match to the OEM part number. In effect, they system is balanced. Pressure + vacuum equals open valve.

    After installing the EGR valve, I connected the main vacuum source to the EGR valve and could tell that it opened slightly (low RPM = low pressure, so partial open only). If I manually open the valve wide open while at idle, it runs pretty rough.

    I hate to claim success after one day, but so far, in 96+ degree temperatures, it appears to have solved the problem. It may take a few days before I claim victory, but looks good so far. Thanks to your help bbob and for the moral support from adalla!

  8. #23
    adalla is offline Cadillac Owners Fanatic
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    Re: 4.5L Valve Pinging / Clattering

    Quote Originally Posted by bantar
    I think I can safely say that my EGR valve did indeed cease to operate properly. It was one of those rare ones that failed closed. Although, I got about 175K miles on the part.

    I bought a new EGR valve and tried to "bench" test it with the engine vacuum and it did not work either, so I sat on this for a few weeks while pondering the next step. Purchased a vacuum guage and confirmed that I'm getting 10-14" hg depending on engine speed. I did put the car in drive and tested the solenoid at various engine speeds. It opened at speed and was closed at idle, so I was left suspecting the EGR valve again.

    I suspected that the egr valve needed backpressure to assist the vacuum and sure enough, after I opened the package with the instructions, it said clearly that the device could not be bench-tested. This very generic EGR valve came with about 50 different numbered and sized orifices which you had to match to the OEM part number. In effect, they system is balanced. Pressure + vacuum equals open valve.

    After installing the EGR valve, I connected the main vacuum source to the EGR valve and could tell that it opened slightly (low RPM = low pressure, so partial open only). If I manually open the valve wide open while at idle, it runs pretty rough.

    I hate to claim success after one day, but so far, in 96+ degree temperatures, it appears to have solved the problem. It may take a few days before I claim victory, but looks good so far. Thanks to your help bbob and for the moral support from adalla!
    Bantar,

    I am glad you finally nailed it! I am pretty sure replacing the EGR valve will fix my knock as well. Too bad I did not order the valve while I was on it. It usually takes a while to be back to a problem I had addressed before. LOL Keep us informed.

  9. #24
    bwood is offline Cadillac Owners Member
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    Re: 4.5L Valve Pinging / Clattering

    you guys shouldnt have to search
    much to find a muffler shop that
    will take a socket and make you
    the tool that bbob described...

    i dont have a welder, but the local
    muffler shop took the socket and
    cut me some metal and welded it
    up for $6...

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