Fuel/exhaust smell seems too strong...dangerous?
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HT4100 4.1, 4.5, 4.9 Discussion, Fuel/exhaust smell seems too strong...dangerous? in Cadillac Engine Technical Discussion; I have an 86 Deville HT4100 (~60K) with ~10,000 miles on a remanufactured engine (Jasper). Since the engine change 8 ...
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    Fuel/exhaust smell seems too strong...dangerous?

    I have an 86 Deville HT4100 (~60K) with ~10,000 miles on a remanufactured engine (Jasper). Since the engine change 8 months ago, I have been noticing stronger fuel smell under the hood with the engine running and it also enters the cabin through the air vents...especially shortly after start-up. Also, when I changed the air filter it reeked stronger than usual of what smells like raw fuel.

    I had a nightmare of a problem with the mechanic who did the installation and they screwed up my exhaust manifold...among a lanudry list of other things...and had to patch weld them after they warped because they installed the wrong gaskets (long story...contained in a previous post). Could this be part of the problem? Sometimes the smell is so strong after starting the car that I have to roll down the windows for a few minutes...the fumes will bring tears to your eyes!

    I have had a new fuel tank, fuel pump, and all routine tune-up items replaced (Delco Rapidfires, new wires, etc). What could be causing this stronger smell? The car seems to run okay (finally) but I am getting somewhat worse fuel economy...reduced by 4-5 MPG than before the engine change. We have had this car since it was new (and this never was the case before), so I know that this is definitely something that has occurred as a result of (or at least in conjunction with) the engine change.

    Also, I have changed the oil 5 times already (about every 2,000 miles) since the new engine was installed and every time it hasn't consumed any oil (literally at the same full mark on the stick). But now...it has used a full quart in the 1,500 miles since the last oil change. The car has been parked in the same spot undriven for a week and not a drop of oil is underneath it, so I don't think its actually leaking. Should I be worried...I know this amount is considered by some to be normal?

    Thanks for any advice on this issue...I don't know much about engines so I can't really get much more specific than this. I would like to know some possible scenarios before I go to a new mechanic and try to tackle this problem. Also, in case it matters, I use Shell 87 octane gas with Lucas fuel treatment and Rotella 15W40 with GM EOS.

    * Also...when I had the fuel pump changed recently I had them check the injectors and they are supposedly not leaking. The previous mechanic also said that my injectors were fine.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    And I did check for codes and there aren't any...

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    First, Northstars normally use oil, not 4.5 engines. It may leak while you drive it. Any smoke from exhaust?
    Second, try to NOT use additives with motor oil and fuel (fuel injector cleaner?) . Injector cleaners are notorious fro distroying fuel pump winding's electrical insulation. It could be the reason you had to replace the pump. They may be hard on fuel injectors as well. Third, check the fuel pressure regulator. Turn ignition on to activate the fuel pump (engine off) and pull the vacuum line off the nipple of the FPR (fuel pressure regulator is close to throttle body and looks like a horizontally positioned black mushroom). There should be NO fuel dripping from the nipple or inside of the vacuum line.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Thanks I will check the fuel pressure regulator as soon as I can. And no, there is no smoke that I can tell from the exhaust. My early-design fuel pump put in 21 years of service (most of which were with a really gunky gas tank from many many years, 15 total, of sitting undriven and rusting) and when I inspected the old fuel pump it didn't have any signs of problems with the winding. I am told its because Lucas fuel treatment/upper cylinder lubricant doesn't contain solvents (which are the real culprit) like most other fuel treatments, so thats why I use it. The only reason I use GM EOS with Rotella is because so many other people on this site and elsewhere highly recommend using it. Normally I agree that additives are a big no-no unless you know exactly what you are putting in, what it actually does and weigh the benefits.

    As for the oil consumption issue, so you are saying that I definitely shouldn't be consuming a quart in 1,500 miles in an engine with 10,000 miles on it? Maybe I should contact Jasper since I am under warranty for another 2.5 years? Somehow I bet they will tell me that is "normal" consumption. Any advice on where I can check for where this oil is going? Also, this oil consumption happened after a long trip (900 miles almost non-stop). I definitely don't want this to get worse since the engine does only have 10,000 miles on it and I plan to keep thos car for many, many, many years to come.

    Thanks!

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    I just went down to see if I could find the fuel pressure regulator based on your description and I can't...I looked in my factory service manual and it gives a nice description of it but no diagram showing where it actually is! As I said, I don't know much about engines, so if you could please give me a little more info on where to find it on my 4.1 (not a 4.5) I would appreciate it! For instance, what will I see connected to it? About how big is it? Where is it in relation to the air cleaner? Thanks alot! Also, when the fuel pump was replaced they checked fuel pressure before and after and said it was normal...I think it was 12 from what I recall. This problem has been an issue since before the fuel pump was replaced but after the engine was replaced. I took out my air cleaner again and it really smells strongly of raw fuel...is that normal?

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    I only can show FPR on a 4.9. Yours will probably look similar. It is somewhere around the throttle body and has a vacuum line attached to its nipple. It is positioned horisontally and is about two inches long.

    EDIT: wow this FPR is probably bigger than your Caddy! LOL

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    4.* engines do not consume any oil unless they leak. A known source of leak is oil filter adapter. My 4.9 leaks all over but it is short of onle 0.5 qtr after 5.000 miles.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Thanks alot for the pic...defintely will help me locate it. And I realized that the car HAD been moved up a little bit and so I did find that there was indeed an oil spot underneath it where it sat for a week. It has basically only been driven once a week for the past couple of months. So over the last 2 months/1,500 miles it lost a quart from this leak...but a properly remanufatured engine with 9,500 miles shouldn't be leaking at ALL, right?!! I guess I will call Jasper and see what they want me to do. Their warranty is 3 years/75,000 miles, I believe. So this problem is probably just going to get worse...the leak appears to be coming from toward the back of the engine and slightly off-center toward the passenger side. No leaking from the oil filter area.

    I will check the FPR tomorrow when its daylight. Thanks again!

    Anybody else have any other ideas on things to check to figure out where this strong gas smell is coming from?

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Have you checked the fittings where the fuel lines run into the TB? If either is leaking, fuel just runs down onto the manifold beneath the air cleaner and evaporates, but it stinks up a storm in the meantime. You have to pull the air cleaner and start the engine to see if they get wet.

    That oil consumption seems silly for a 10k engine. Make sure you don't have any greasy slicks in the coolant.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Actually noahsdad, now that you mention it, there is an indention "well" in the top of the engine block under the air cleaner sort of behind the throttle cable adjustment area. In this little "well" there has been some slightly greasy, filmy looking "condensation". Well...now I am guessing that it may be what you are talking about. When I got the oil changed last time they pointed it out to me but I figured it was just water with a little surface oil because they had to rinse off the engine area from spilling some oil in there (yeah they were geniuses!). I hadn't thought about it in a while because it was only about a teaspoon worth of fluid at the time that I could tell wasn't oil or coolant or any vehicle fluid I was aware of...duhhh its probably gas!

    I looked just now and it looks like the mixture of a little surface oil, dirt and dribbles of gas collecting in that little well...maybe 1/2 teaspoon still hanging out in that area since the car was driven this afternoon. I won't be able to tackle the issue until the weekend but I will pull off the air cleaner and see what I can see. Honestly I don't know what lines are what but I'm sure that I can just look for the one(s) that's leaking!

    Yeah...I don't think its oil consumption so much as it is an actual leak now that I further investigate the areas where the car was parked for long periods. Because I have to park on the streets in my neighborhood, my car usually stays in one spot for a several days to a week and then moves somewhere totally different...makes it hard to tell what is "your" oil spot and what is someone else's oil spot!!

    Thanks for your insight!

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    There is no external fuel pressure regulator on the 4.1 and 4.5 TBI engines like HUF pictured--it's contained in the throttle body. These RARELY go bad on the TBI engines. I agree with noahsdad--check your fuel lines going into the TBI. Try turning the key to the "on" position and leave it there, with the engine off, for about 5 mins. Watch for drips out of the fuel lines. If you need to, disconnect the fuel line and place a small o-ring in the fitting. This almost always cures the leaks.

    For some reason, when you disconnect these fuel lines, it's very hard to get them to not leak after reconnecting them. My guess is that your genius engine installers didn't check to see if the fuel lines were dripping after they reconnected them. You do NOT want to overtighten the lines, or you'll kink them. The o-ring trick works very well and is perfectly safe.


    The oil leak may be coming from the rear main seal area. On these cars, Cadillac used a LOT of RTV sealant to seal off the oil pan/main bearing caps.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Since this "new" engine is already leaking (argh!!!!!!!!!!!!) then is that most likely a Jasper issue from the factory or is that something that could be related to the poor installation job? I did get back all the LABOR money that I paid the idiots for this engine/trans installation (finally...had to dispute it with Visa) and definitely am NOT going to be returning to the same shop. But before I go pointing fingers I would like to know what the likelihood of this being a factory problem with a seal or something.

    Thanks...

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    If there is a fuel leak, that's an installation issue. Awadecki is right, it's almost impossible to re-connect those lines without using the o-ring solution. Works like magic.
    The oil loss is a different matter. Odds are Jasper's warranty doesn't cover external leaks (except maybe main seals), but if the oil is actually being consumed, or mixing into the coolant, you probably have a good claim.

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Oh my well it DOES look like there is oil in my brand spankin' new radiator (but no coolant in the oil...been there done that twice with the old engine between 30-40K so i know what that looks like...milkshake!). My coolant is the green kind and of course I used the pellets...usually it looks kinda green with brownish pellet stuff...but now it has an iridescence like an oil slick and is pretty darn brown. If it weren't a brand new radiator I might have chalked it up to rust or something...but I KNOW it can't be rust already. What does that mean? Is my new radiator ruined...is my new ENGINE ruined? Someone please tell me this is a Jasper problem that I can get them to warranty...I know the HT4100 isn't the best engine in the world but it should give me more than 10,000 miles before doing this to me, right?!!

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    Re: Fuel/exhaust smell seems too strong...dangerous?

    Since the subject of the oil in the radiator is off topic from what I originally posted in this thread, I started a new thread re: Remanufactured HT4100 - 10K and oil in radiator for that discussion.

    I am going to hold off on addressing the fuel smell issue until this oil leak gets resolved. Thanks for reading and offering your knowledge...

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