Refilling colant reservoir every 2 weeks, misfire at idle

mike93 · #1 (**permalink**) 10-20-09, 07:01 PM

Hey everyone it's me again today while driving home i noticed a lil smoke coming from under hood when opened hood don't see no leaks around the motor anywhere not from timing cover or water pump and no leaks under car car still stumbles under acceleration and doing it more again now and missfire at idle with those symptoms can it be the intake manifold gasket otherwise car runs greatnew hoses water pump thermostat please help me!

drewsdeville · #2 (**permalink**) 10-20-09, 10:18 PM

The intake gaskets on the 4.X's can't really leak coolant externally. If you are seeing smoke, you still have an external leak somewhere that you haven't spotted. If you are leaking coolant onto ignition parts, this can be causeing your misfire. All I can suggest is that you look again. Has to be leaking somewhere...

mike93 · #3 (**permalink**) 10-20-09, 10:38 PM

So they can't leak Externally? Maybe it's the heater hoses that's the only hoses I havent changed and rite underneath is the exhaust manifold but like i said everything else is new upper/lower radiator hoses water pump and thermostat idk what else it can be no antifreeze on the floor or anything

mike93 · #4 (**permalink**) 10-20-09, 11:09 PM

Also sometimes when I start the car the idle goes up and down without giving it gas or anything

**Ranger** · #5 (**permalink**) 10-20-09, 11:18 PM

That could be a vacuum leak or a bad ISC motor.

drewsdeville · #6 (**permalink**) 10-20-09, 11:27 PM

While anythign can happen, it's pretty unrealistic. The coolant passages through the intake gasket run on the outside (right next to) of the runners for cylinders 1,7,2, and 8. Take a look.

I remember asking you this before, but can't remember if you checked or not. Make sure to take a look at the heater "T" back by the firewall. Common leak point. Otherwise, just follow the cooling system around the motor, even in inconspicuous areas. The coolant has to be going somewhere, since you are seeing steam.

Some "hidden" area's to check are the water inlet, which is located behind the timing cover and water pump, above the AC compressor. Check the water crossover pipe that runs under the harmonic balancer. Dont' forget the there are coolant passages that pass through the timing cover as well, so make sure the timing cover gasket isn't leaking (also unlikely) as this could also result in simultaneous internal intrusion.

That said, make sure to check the condition of your oil for water contamination.

mike93 · #7 (**permalink**) 10-20-09, 11:32 PM

Ok will check oil in the morning i checked the timing cover and no leaks just tiny bit of seepage but i gotta check the
T at the firewall after i shut the car off and checked everything i started it up for 5 mins and nothing then drove home and saw no more smoke and the smoke i did see was very very little smoke and the cooling fans came on which is a good thing

drewsdeville · #8 (**permalink**) 10-20-09, 11:47 PM

A tiny bit of seepage is something worth considering. At operating temp, the cooling system is under pressure. What looks like seepage when the car is sitting could be a serious leak under operating conditions...

drewsdeville · #9 (**permalink**) 10-20-09, 11:49 PM

Quote:

Originally Posted by mike93

Also sometimes when I start the car the idle goes up and down without giving it gas or anything

This could be A LOT of things. Have you checked your codes yet?

mike93 · #10 (**permalink**) 10-20-09, 11:51 PM

When I checked the car the car was under pressure at operating temp and that's when i looked at the timing cover and saw a little seepage so i know it's not that

revdowrong · #11 (**permalink**) 10-21-09, 12:18 AM

you might want to check the raditor cap. If old they will not hold pressure as well and will start to leak slightly. This happen on my car, and also check to make sure your thermostat housing is not loose. Also check the upper radiator hose corner if it has the plastic covering the corner of the hose because this could also start a hidden leak. And check the waterpump for leaks with the engine running. 4.9s are known for eating through waterpumps.

mike93 · #12 (**permalink**) 10-21-09, 12:34 AM

Ok waterpump is new 4 months old and when i opened the hood the radiator cap was a little loose i tightened that and then saw no more smoke but will check it more tomorrow but no codes and really misfiring at idle

HUF · #13 (**permalink**) 10-21-09, 01:00 AM

Start the engine, open the hood and lift the throttle lever up with a finger to increase RPM to some 3500-4000. Watch carefully for leaks. The plastic T (called heater valve) may leak UNDER PRESSURE. It is on top of the engine behind throttle body. Some connections, radiator side tanks, etc. are known sources of leaks as well.