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Sue
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What could be the knocking noise coming from the engine area?

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There is a knocking sound that started coming from my car a couple days ago. Its not a ticking or a clanking knock. It's more of the sound when you take your fisted hand and starting from an inch above a wooden desk top tap at about 1 knock per second. (Its more a deep and slow soft knock than most of the sounds I've been hearing while researching online).

To add, I have had a problem with leaking coolant from the thermostat housing gasket, well there was no gasket. We replaced that, now it doesn't leak, but the coolant is still going somewhere, I don't know where yet....

Any ideas on what the knock is and possibly where my coolant is going? And the fixes you think would be best.

Thanks for any suggestions. :)

Edited by: mayer ( )

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oldturkey03
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Sue not sure about your engine size but the 3.4 engine are common for intake gasket leaks and the 3.8 is known for the intake manifold going bad. If the noise you hear is a fast tap or clatter near the top of the engine, it could be valve noise which would require you to have some cylinder head work done. same noise can come from wore camshaft its a tapping noise. If the noise is a steady metallic rap it may indicate a rod/rod bearing, a quick steady tap may indicate lifters or cam lobe, while a clatter may be loose/worn rocker arms. A low rumble or knocking noise could be caused by a bad rod bearing on the crankshaft. Here are a a couple of sites that tell you a bit more http://www.remanufactured.com/Engine_Noi... and http://www.aa1car.com/library/engine_noi... As you can tell there is a multitude of problems that can come with that noise. Trey to trouble shoot a little at a time. Check your plugs see what they look like at the business end. You can get a lot of info from that also make sure your oil and coolant levels are okay. May be get somebody to do a compression test and a leak down test to see if your valves/rings etc. are okay. What does your exhaust fumes look like? White smoke? black smoke? White smoke could indicate that some of your coolant gets into the combustion area, black smoke excessively burning oil. Good luck to you and hope this helped a little.

+ really excellent answer The coolant is probably going out your tail pipe in the form of white smoke. You may have a vacuum diaphram allowing coolant to be sucked into engine such as heater control valve. Antifreeze and water do not combust and will cause knocking. Did the engine ever freeze after running out of antifreeze?

mayer,

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ABCellars
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Insofar as your leak goes obviously check your hoses for loose clamps any hoses that are dried out/cracking if they aren't leaking now they soon will be and the radiator. One thing many people overlook when looking for the source of coolant leaks is the water pump. It has a weep hole and when the pump bearings are shot it will begin to leak to let people know to look for a problem. If you have looked and looked and not found the leak. It is probably from the water pump. It starts out dripping slowly as the seal wears from the play in bearing's movement. Until the pump is really ready to go it only drips out when the engine is running.

You have not given much to go on to reasonably ascertain what would cause the sound you mention. Does it happen when you are stopped and the engine is idling? When stopped and pressing on the gas does it increase, slow down or stop? Have you had exhaust work done lately? Many times people don't run the pipes properly and they will thump against something as you describe. I would check your engine and motor mounts if one of them has been compromised it can give the sound you describe while the car is idling. If it only happens when you are going down the road everything I've mentioned so far and a whole lot more could be causing it. From what I have said, oldturkey03 stated and your own experience it is going to be somewhat hit and miss diagnosing the cause(s). If it is coming from the motor, a sensor is more than likely picking it up and in part defining the cause. I would suggest hooking it up to a diagnostic scan tester to help determine the cause. A number of people are not aware of this but many auto parts stores, including AutoZone, offer free diagnostic hook-ups. I would call around to find an auto parts store that does the free diagnostic scan on your car's computer. While they have it hooked up casually ask them about the noise and possible causes. Most of the counter people have a fair amount of experience working on cars and may very well know the cause. This is not a direct solution to the problem. But, it is kind of hard not being able to hear the noise or knowing when it is happening to give you any reliable advice besides take it to someone that can hear it and determine when it is happening. While this is not a direct solution to your problem it is the most economical and feasible one I can think of.

NOTE: The computer diagnostic scanners that the auto parts store will hook up for free is the same one(s) used by many mechanics who will charge you for the service.

Edited by: ABCellars ( )

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braylingroff
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Bad bearing, lifter,push rod ,flywheel, piston skirt, timing ,piston,distributor,number of things really

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brandon
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Hiya iv got a mark 4 golf S 1.4 16valve on a 1998 reg when a start the car a can here a tappin noise cumin from engain and when a accelerate it get faster any idias wot a could do 2 sort it

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samimi
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What is the cause of engine noise resulting from inappropriate camshaft?

samimi, what would you consider an "inappropriate camshaft"?

oldturkey03,

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