egr valve
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HT4100 4.1, 4.5, 4.9 Discussion, egr valve in Cadillac Engine Technical Discussion; i hear alot of people on here talking about cleaning out their egr vvalves, i have an 83 fleetwood with ...
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    Adumb's Avatar
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    egr valve

    i hear alot of people on here talking about cleaning out their egr vvalves, i have an 83 fleetwood with the 4100 and fuel injection so i was wondering how i would get to the egr vavle and how to clean it. thanks.

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    Re: egr valve

    I generally use choke or brake cleaner and compressed air to clean them.

    Spray in the choke cleaner into the pintle and let it sit for a bit. Then open the valve and slowly blow the air in. Do it on both sides until all the carbon has been cleaned out. Repeat as necessary. When it is cleaned, you should not be able to blow any air through the valve.

    But this will not fix an EGR valve with a bad diaphragm.

    Mike

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    Re: egr valve

    i was talking to my dad and the impression i got was that the egr valve is a one way check valve that releases pressure in the case that pressure gets into the valve covers. does that sound wrong? right? or is there more to it?

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    DrDave is offline Cadillac Owners Fanatic
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    Re: egr valve

    think that's the pcv valve? egr is exhaust gas recirculation, and is used to cut down the nitrous oxide (?) gas from the combustion chamber. It's open during part throttle conditions, and requires backpressure to operate (you won't be able to check it by simply applying vacuum to it and watching for diaphragm movement).

    Dave

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    Re: egr valve

    Yes, the EGR valve is used to lower NOX emissions. NOX is created under high combustion temperatures. By allowing a metered amount of spent exhaust gasses (an inert gas) into the intake, it cools peak combustion temperatures thereby controlling NOX emissions.

    Up until the mid 90's, all the valves were vacuum operarted. The earliest examples used ported vacuum from the carb, the faster the engine speed, the more vacuum and the more the valve would open. Later exhaust backpressure came in, but the valves continued to be vacuum operated.

    Today pretty much all the EGR valves are operated electronically and controlled by the PCM via 3 solenoids on the valve itself.

    Mike

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    Re: egr valve

    Quote Originally Posted by Adumb
    i hear alot of people on here talking about cleaning out their egr vvalves, i have an 83 fleetwood with the 4100 and fuel injection so i was wondering how i would get to the egr vavle and how to clean it. thanks.

    Your EGR valve is fine. Leave it alone. The EGR valve most often mentioned for cleaning is on the Northstar engine...different valve, different part, different design, different system, diffferent problem. Your engine with the throttle body injection rarely , if ever, needs service of the EGR valve or the EGR system.

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    Re: egr valve

    Quote Originally Posted by guidematic
    Yes, the EGR valve is used to lower NOX emissions. NOX is created under high combustion temperatures. By allowing a metered amount of spent exhaust gasses (an inert gas) into the intake, it cools peak combustion temperatures thereby controlling NOX emissions.

    Up until the mid 90's, all the valves were vacuum operarted. The earliest examples used ported vacuum from the carb, the faster the engine speed, the more vacuum and the more the valve would open. Later exhaust backpressure came in, but the valves continued to be vacuum operated.

    Today pretty much all the EGR valves are operated electronically and controlled by the PCM via 3 solenoids on the valve itself.

    Mike

    True, but you are describing one specific type of electronic EGR valve with the three solenoids on it. That type is often referred to as a "picolo" valve as it resembles a picolo. Each of the three solenoids activates a separate pintle that is set to flow a specific amount of EGR...by opening the different pintles in various combinations the desired amount of EGR is introduced.

    The type of EGR used on the 4.1/4.5/4.9 engines are all vacuum operated, backpressure EGR valves with electronic control solenoids (activated by the PCM) to meter and control the vacuum signal to the EGR valve.

    The Northstar uses an electronic EGR valve that is a linear motor style of valve that does not have three solenoids.....it has a single "can" with a wire winding inside and feedback transducers for pintle position. The pintle position is controlled by the PCM via the wire winding and pintle true position is verified to the PCM via the feedback transducer....so...it doesn't have the three solenoids that you mention.

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    Re: egr valve

    so what type of parts should i clean or probably need cleaning on my ht4100? i imagine there have to be some

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    Re: egr valve

    Actually, very little.

    Things like spark plugs and plug wires can wear with time as well as the rotor inside the distributor and the distributor cap. Those usually start to show some sign of problems as a misfire or roughness will start to show up.

    The most important thing for that engine is to keep the oil changed regularily. Use one of the heavy duty diesel oils such as 15W40 Delo or Delvac or Rotella oil. Look on the shelves at the discount stores for one of these. Much better than other oils for the HT4100 as they have more anti-wear additives that that engine needs as it has flat tappets, a spur gear oil pump, rubbing elements at the rocker arm pivots and a distributor gear...all need more of the anti-wear agents the HD diesel oils have.

    The single biggest maintenance item is to keep the cooling system full of fresh coolant..it needs to be changed ev ery 2-3 years or 24-32K miles at the most. Fresh coolant is needed to keep the anti-corrosion additives in the coolant from becoming depleted and causing major engine problems due to internal corrosion of the engine.

    You absolutely MUST use the GM cooling system supplement in that engine to guard against internal coolant leaks or seepage into the oil. This is a mandatory thing. Use the forum search feature in the forum tool bar above to search the archives using "coolant supplement" and read my posts for more information on this. If there is any doubt as to the freshness of the coolant or the fact that the coolant supplement is installed (minimum of 6 pellets in the fresh coolant installed at the radiator cap) then refresh the system immediately and/or add the supplement.

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    Re: egr valve

    yeah, i just got the car in november and before that it was garage kept for a couple of years so i would guess i better get on that coolant change. wear can i buy the gm cooling system supplement? thanks.

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    Re: egr valve

    bob wasnt there something about the timing geare in these 4.1s he should look at also ?

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    Re: egr valve

    Quote Originally Posted by Stoneage_Caddy
    bob wasnt there something about the timing geare in these 4.1s he should look at also ?

    Yea, sooner or later that will need a new timing gear as the timing gear on the cam has the nylon teeth and after 22 years it is likely ready to shed some teeth.....better put that in the budget also. Hopefully with the lower mileage it has a little life left in it although those gears were usually 10 year/100K parts...whichever came first.

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    Re: egr valve

    ok did a search heres what i found (trying to save bob some time)

    I have a 1984 Eldo 4.1L front wheel drive. I was getting a low oil pressure light at any stop. After much checking I decided to remove the oil pan. I found lots of nylon pieces in the oil pan. I looked at the timeing chain from under the bottom and it looked metal. Is a nylon timing chain part metal? I could not get a good look.
    Quote Originally Posted by bbob
    your engine has a timing gear on the cam that is aluminum with nylon teeth. Sounds like it is on it's last leg......

    Unless the front of the engine clearly shows signs of tampering...i.e...rounded off bolts, cleaned up spots, etc... I would assume that the original timing gear is in there and that it needs to be replaced IMMEDIATELY. If teeth have fallen off and are in the pan then it is moments away from self destruction and you DO NOT need that grief.

    What you see on the crank is the bottom timing gear and it is powdered metal and will likely run "forever" but the upper, larger gear is the nylon toothed one. Replace it with the powdered metal gear from a 1988/89 4.5 liter engine and it will never shed teeth again. Those parts are interchangable and will eliminate any possible timing gear failures in the future.

    Those nylon toothed gears are good for 100K/ten years whichever come first so yours is about due...........
    The 82-87 4.1 had the nylon teeth on the timing gear for the camshaft. In 1988 the 4.5 engine got a powdered metal timing gear on the cam that is virtually lifetime......Replace it with the powdered metal gear from a 1988/89 4.5 liter engine and it will never shed teeth again. Those parts are interchangable and will eliminate any possible timing gear failures in the future.

    here is the rest of the thread , i dont want to make anyone worry just trying to help :
    http://www.cadillacforums.com/forums....1+timing+gear

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    Re: egr valve

    man, now im paranoid, haha. thanks for the help though, ill keep that in mind.

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    Re: egr valve

    Quote Originally Posted by bbob
    True, but you are describing one specific type of electronic EGR valve with the three solenoids on it. That type is often referred to as a "picolo" valve as it resembles a picolo. Each of the three solenoids activates a separate pintle that is set to flow a specific amount of EGR...by opening the different pintles in various combinations the desired amount of EGR is introduced.

    The type of EGR used on the 4.1/4.5/4.9 engines are all vacuum operated, backpressure EGR valves with electronic control solenoids (activated by the PCM) to meter and control the vacuum signal to the EGR valve.

    The Northstar uses an electronic EGR valve that is a linear motor style of valve that does not have three solenoids.....it has a single "can" with a wire winding inside and feedback transducers for pintle position. The pintle position is controlled by the PCM via the wire winding and pintle true position is verified to the PCM via the feedback transducer....so...it doesn't have the three solenoids that you mention.

    I guess I've been away from the front lines awhile. The 3 solenoid type were just getting popular when I left the dealer. I totally forgot about the stepping motor type in the Northstars.

    Oh well. I'll just have to stick with the old timers.

    Mike

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