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Old 04-02-2015, 12:01 PM
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4.0 startup knock

97 wrangler 4.0 when started knocks and sounds like bottom end but when temp comes up quiets down significantly. Any suggestions other than oil change, seafoam or any of the likes?

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Old 04-02-2015, 01:10 PM   #2
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Does it sort of sound like a diesel engine? I think that's a common sound. Mine does it too and I've changed lifters and the timing set.

08 JKU Rubicon, 3.5" Rock Krawler springs, Fox shocks, 18x9 Fuel wheels wrapped in Cooper 37x13.5 STT. more to come...
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Old 04-02-2015, 03:22 PM
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Sounds like that after it runs for a few, initial start up is definitely a knock, sounds like bottom end but if it was should not go away when warm. Or so I would think
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Old 04-03-2015, 11:40 AM   #4
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I've been told by SEVERAL knowledgeable people that the noise is caused by wrist pins and is one of those norms with the 4.0. I just sea foamed my entire system and it helped quiet mine tremendously. I'll find that link and post it up.
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Old 04-03-2015, 11:44 AM   #5
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Apologies to Brunetto, but I couldn't figure out how to link to his write up, but here it is.

I have finally decided to get off my lazy butt and write a tutorial on how to seafoam your car. Many of you are familiar with seafoam; some have no idea what it is. Well, for all those that are interested, seafoam is multipurpose, 100% petroleum product you can pick up at any local auto store (Napa, advance, AutoZone, etc). It is used to clean carbon buildup from your engine, clean your injectors, and clean your oil and a whole lot more. to familiarize you with the products, this is what I am talking about:


Seafoam Deep Creep:

okay now that you all see what seafoam is, let's talk about what it's used for:

Uses of Seafoam

I would first like to state for the record that seafoam is NOT a power adder. All seafoam does is clean out the gunk inside your engine and injectors. This will do nothing more than restore any horsepower/fuel economy you have lost due to years of dirt and grime inside your engine. Any power you pick up along the way is because it has just been suppressed by the filthy engine and is now free again.

if you are losing power and mpg due to carbon buildup, if you are experiencing pinging and if you're having trouble passing emissions test, seafoam may be your answer (yes, seafoam will actually reduce your emissions if carbon buildup is causing dirty exhaust fumes!). Feeling the pinch at the pump lately? Well, seafoam can be used to pick up a few extra mpg you have lost over the years and reduce or eliminate your engine ping by cleaning out your cylinders!

What You Need to Seafoam Your Engine:

in order to maximize your engine's fuel economy and performance, you should do a full engine treatment. in order to do so, you will need a few things:

- 2 cans of seafoam (1st picture above)
- 1 can of seafoam deep creep (2nd picture above)
- flat head screwdriver
- pliers
- 1 long, skinny funnel

okay, now that you have all the necessary tools to complete the job, let's talk about how to use seafoam:

How To Seafoam Your Car:

Part One: Injector Cleaning

this is the easiest part of the process. Simply drive to the gas station and completely fill up your tank with 91+ octane gasoline as usual. Take 1 of the 2 cans of seafoam in the requirements above. This can of seafoam will be poured directly into your gas tank. Now, seafoam makes a great product but they didn't think too hard when they designed their can. You need a funnel in order to dump it into your gas tank. Do not try to be cool and try and beat gravity by jamming the can into your gas tank. I tried that. All I got was a car that smelled like gas and wasted seafoam on the ground. Take the long skinny funnel, put it in your gas tank, shake the can of seafoam up and pour the entire can of seafoam into the tank. Then, take your car for a nice ride so the seafoam swishes and mixes in your gas tank. The seafoam will clean out your injectors nicely. Try and run this tank pretty low before filling up so you don't dilute the mixture with more gasoline. This way, you get the maximum cleaning power of seafoam.

Part Two: Cleaning Your Oil System

as you all should know, f-bodies require 5.5 quarts of oil. Seafoam is to be added directly into your crankcase in order to cleanse the oil. Yes, you heard me; you're pouring a foreign mixture directly into your engine oil. This can be scary for newbie’s. Never fear, seafoam is 100% petroleum. It is as harmful to your engine as water is to your skin - not harmful at all. The correct measurement for seafoam is 1.5 ounces per quart of oil in your crankcase. Simple math tells us:

(1.5) X (5.5) = 8.25 ounces

a can of seafoam is 16 ounces, so for simplicity's sake, we'll add half a can directly into the ENGINE OIL spout. NOTE: I recommend pouring the seafoam into your oil when the car is cold. I would not recommend pouring a room temperature liquid into 200+ degree oil after the car is hot. Last thing you want to do is shock your valve springs.

Run the seafoam in your oil for NO MORE THAN 250 miles! Seafoam is very aggressive. Your next oil change will be black as Satan’s heart and likely thicker than usual. I would not recommend running this oil very long in the car as your oil filter is going to have quite the time on its hands and the oil won't be in the best of shape afterwards. I’ll say it again. Change your oil less than 250 miles after you put seafoam in your crankcase! I personally recommend running it 100 miles, then changing your oil. That should be plenty for the seafoam to get most of the gunk out.

Part Three: Top End cleaning

here comes the fun part: cleaning the engine internals! NOTE: park your car in a VERY WELL VENTILATED area for this step as high amounts of toxic fumes will be pouring out of your car.

As you recall, we have half a can of seafoam left. This half a can will be used to clean out your cylinder banks. In order to do this, we need to locate a vacuum line to directly feed the seafoam into the engine. The favorite vacuum line is the brake booster line. for those unfamiliar with the brake booster, here is what it looks like:

(sorry for the image quality, it was getting dark and that's the best my cell phone can do )

the brake booster is the big, black saucer shaped object behind the brake fluid holder against the driver's side firewall in case you can't tell by the picture.

We will be sucking the seafoam into the brake booster hose marked by the red arrow. (Note: some people prefer to suck the seafoam in through the PCV line. this is also acceptable, although I have never done it.)

First thing you want to do is start the car and let it warm up until the engine reaches closed loop. Basically, start your car and wait for the engine to warm up to normal operating temperatures (5 - 10 minutes depending on outside temperature). After the engine is nice and warm, turn the car off. Now we're going to disengage the brake booster line.

For this, you may need a pair of pliers and a flat head screwdriver. There is a little metal clip holding the brake booster hose to the brake booster. You want to take a pair of pliers, compress the clip and slide it down the hose a few inches. Now that the clip is out of the way, you need to disengage the brake booster hose. This can be a bear if you've never done this before. My car had 80,000 miles on it when I sea foamed it and that sucker was stuck on there tight (it's a vacuum line, it's glued by high pressure). You may need to take the flat head screwdriver and jam it into the vacuum line and wiggle it off the brake booster. This may take a while. It took me a lot of pressure to get the hose off the booster. You may have to pull pretty hard.

Once the hose is off, you're going to want to find a small funnel that will fit into the brake booster hose. I do not recommend simply jamming the hose into the seafoam and letting the engine suck it up. This makes it very hard to control the amount being sucked up and could flood the engine far too fast cause it to prematurely stall out.

Now that you have a funnel jammed into the brake booster hose, start the car. You’ll notice your rpm's are very high, likely around 2000-3000rpms. This is because your brake booster hose being disconnected is causing a massive vacuum leak. You’ll be able to feel the engine sucking air down the funnel.

At this point, you have half a can of seafoam left (8 ounces). You should, in your head, divide that into three equal parts. You’re going to want to SLOWLY pour the first two thirds of the seafoam left in the can into the engine via the funnel. The engine will start to sputter and choke as you pour in the seafoam. You DO NOT want your engine to stall out. Go as slowly as possible pouring the seafoam into the engine as necessary so the engine does not die. Do this for the first two thirds of the mixture. With the final third of the seafoam, quickly dump it down into the funnel. The idea here is to stall out the motor, suspending the remaining gulp of seafoam in the cylinder banks (don't be alarmed if your engine bay is smoking the entire time this is happening). If your car does not stall, quickly run and turn off the key.

Do not start the car for at least 15-20 minutes. We want the seafoam to soak in the motor good and hard to get all that nasty carbon out of the engine.

While the engine is sitting and soaking, with the key out of the ignition of course, get that bottle of seafoam deep creep I told you to buy.

Seafoam deep creep is to be sprayed inside your throttle body. Disconnect your hose running to the throttle body so your throttle body blade is showing. Get a friend to push down on your gas pedal so the throttle blade opens. If you don't have a friend at your disposal, a brick or something will do just fine to hold the gas pedal down, anything to keep the throttle blade open. Again, your engine is to be OFF during all this.

once you can see inside your throttle body opening, spray seafoam deep creep into throttle body, fully soaking the blades, the bottom, top, and up and down into the intake manifold behind the throttle body. Use a good amount of seafoam. Don’t be too conservative, but the whole can is far from necessary. Use your judgment. Get it in there nice and deep but there's no need to flood anything!

Reconnect the throttle body hose, the brake booster hose, the clip back on the brake booster line and anything else you may have disturbed during the sea foaming of your car.

Now we will just wait for the remaining time to pass before you can start your car back up.

Okay, now that 15-20 minutes have passed, it's time to start your baby back up. This may be a challenge. The engine is flooded with liquid so it may be a lot harder to start that usual. This is completely normal. Once your car is started, let it idle for a good 10-15 minutes. Your car is likely to smoke profusely. If it does not, lightly tap your gas pedal. Do NOT rev the engine like a madman. When I say lightly tap, I mean gently tap the rpm's up to no more than 1500. A blip is all that is necessary. If it doesn't smoke too badly, it's because your engine just wasn't that dirty.

After the car has been sitting idling for 10-15 minutes, take the car out for a spirited drive. The key word here is spirited. You want to rev your car nice and high and get all that seafoam into all the valleys of the engine. This is the perfect excuse to completely run the balls off your car. If you look behind you, you will likely see a long trail of blue smoke dusting out the entire highway. Say good-bye to the culprit carbon buildup killing your power, gas mileage and causing your engine to ping. It’s Mother Nature’s problem now

congratulations! You have successfully sea foamed your car. be amazed as your car revs faster, your gas needle moves slower, your idle is smoother and yes, even your exhaust smells less noxious (except maybe you ORY guys...you're screwed either way ).

NOTE: seafoam is O2 sensor safe and will not damage your spark plugs or catalytic converters with responsible use. This means as long as you're not sea foaming your car constantly and using far above the recommended dosages, you should be fine. It’s probably good to do this process every 10,000 miles to keep your car in tip-top shape.
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Old 04-09-2015, 07:34 AM   #6
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Its Great Stuff

I have been using it for years on boats. Pickling them for winter lay up, and then to get them running great for the summer. I bought a boat years agao with twin small blocks. both engines smoked like a sift. Did the whole treatment stuff like you are telling, had a few upset neighbors but after runningabout a hour and then changing oil and filter. Ran like a charm and NO SMOKE. I have only one thing to add to doing this. After you change the oil after using it in crank case, run it for a thousand miles and change oil filter again. Open up oilfilter and see whats in the filter. You will then know for sure if it is cleaned out or not. Also its a good idea to do this ever so often to check for metal fillings. HOHOHO
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Old 04-09-2015, 12:37 PM   #7
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One other thing. What kind of oil filter are you using?
If you have one with a stuck check valve in it, it will allow the oil to drain out back into the sump. When you start the engine, there is no oil pressure until it fills the filter back up and then moves on to the rest of the engine.

Could be something as simple as this too.

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God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.
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