I have a 1999 ford f250 super duty 6.8 litre engine. My service engine light came on about the same time it started running rough ie: shuttering at low speeds. I had it put on a meter and the codes came back p171 and p174. I started to replace the plugs and boots and discovered anti freeze in the two front plug holes. I have already replaced the pvc hose as well. Is it time for replacing the intake manifold gasket?
Could be intake, could be head gasket. take the radiator cap off and fill it to the brim with water, then start the engine and look for bubbles in the water. you might have to top it off while it's running to get a good reading. if any of the plugs you took out were much cleaner than the rest, or had a white crust deposit on them, the head gasket is probably the culprit.
Robert, Thank you for your help. I am going to do what you suggested but, I actually took it to a mechanic and they pulled the plugs as i watched. The plugs were more rusty and wet . They told me where it was leaking it was more likely the intake than the head. If i had a head gasket leak would i have water in my oil? I am just trying to not get ripped off as i am disabled and cannot do the work myself anymore. I greatly appreciate you taking time with me.. for now i will do the radiator thing. Thanks again
I've seen a wide variety of symptoms with weak head gaskets. sometimes they act like reed valves and only push compression into the water system without actually pulling water into the cylinders. I've seen compression go from one cylinder to the next without affecting the water or oil. I've seen intake gaskets leak as well, so some exploratory surgery is necessary for yours, it seems. if they lift the intake and the gasket shows no signs of failure, they may as well continue and remove the heads.
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Could be leaking intake manifold gasket but check for leaking coolant hose or check the coolant overflow jug it could be leaking its on top front of the engine.
SOURCE: 95 GMC Jimmy 4.3l W vin rough idle
My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.
SOURCE: service engine soon light keeps coming on. Now low coolant light
I would start by doing an oil change myself so you can examine the oil and look for water/antifreeze in it. You will be able to see it separate from the oil and you can smell the antifreeze. If there is then you have a leak between the water jacket and the heads somewhere. More than likely the LOWER intake gasket is leaking into the head. You said they replaced a gasket but was it the UPPER or LOWER? If it was the LOWER did they use RTV in the correct areas? Did they torque the intake bolts to the correct pressure and install the bolts correctly? I know you don't have these answers but these could all be part of the problem. It may be leaking more at #2 cylinder and causing it to foul more than the others. Also just because a mech pressurized the coolant system and didnt see any change in pressure (hopefully he wasn't just looking for visible leaks) the issue may not happen until the engine is hot, as metals behave differently when heated, especially aluminum which the LOWER intake is made. Have a mechanic or mechanically inclined friend (gearhead) remove the #2 plug wire, then kick the engine a few times without starting it, enough to let any fluid get into the chamber, this would include gas btw. Then remove the plug and look for any wet residue on the plug, gas will evap. quickly, antifreeze/oil won't. again try to smell the residue and if necessary, lightly touch some to your tongue, antifreeze has a sugary sweet taste that is easily detectable. Remember any time you are working with chemicals such as waste oil and especially anti freeze, minimize spills and clean them up quickly and completely and place the spent fluid in a sealable container and take them to a collection center for disposal. Waste oil is a carcinagin (cancer causing) agent and antifreeze (glycol) new or old will kill any animal (child, dog, cat,etc) that ingests it. Many auto parts stores and some other retailers that sell oil and antifreeze will take your wastes if you bought the replacement fluid from them, check before you buy.
SOURCE: service engine soon light on 2002 chevrolet tahoe stays on
That normally means that you have a issue with your gas cap try replacing your gas cap first then diconnect the negative terminal of the battery for about three minutes to clear the memory and start the truck again
SOURCE: 2001 Galant service engine light on & won't stay running/ runs rough
Try this: Disconnect the ecm control (where the air filter is housed)
Let me know if that worked.
SOURCE: 1999 Chevy silverado 5.3 engine setting codes p171
oxygen sensor failure
P0171 System too Lean (Bank 1) - Read Our Article On Oxygen Sensor Codes For Help With This Generic Check Engine Light Code
P0174 System too Lean (Bank 2) - Read Our Article On Oxygen Sensor Codes For Help With This Generic Check Engine Light Code
hope this is a bit of a push in the right direction ...
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