Gunk and Film?

[chill]

I recently bought an 06 libby with 97k, v6. I was poking around at it and found that the filler neck for the oil has a gunk under the lip. looks like a build of used oil is kinda gummy and black. I'm thinking it's just build up of old oils used in the past. Being a used vehicle I do not know the type of oil, that was used obviously.

Also behind the plenum in the TB is a film of a black substance that was a little sticky. Again a build up of some sort i'm thinking.

My previous yrs. experiences is with 4 cyls. I am new to this size motor and jeep motors in general. Having said that, I have not run into this before, prolly because i clean and change parts and fluids often. SO, is there cause for concern? or have you all seen this in our motors before? I gather that it is really just lack of attention from the pre. owners. I'd like to flush out the motor but am afraid of blowing goo into the motor and seizing up.

 

[streetglideok]

The gunk under the oil cap is a lighter color isnt it? Chrysler had issues with the 4.7L and 3.7L doing that. Far as I know, the ones that did this had the little baffle stick that slid down where you pour the oil into. New ones dont have them that Ive seen, and they havent had that gunk buildup. Seems to stem from lack of ventilation of the crankcase in that area, causing moisture buildup. The gunk in the throttlebody is common, and just needs to be cleaned with brakeclean, or a throttlebody cleaner. It can cause running issues if left neglected.

 

[Ry' N Jen]

We've got a little bit of black tar like schmew on the inside of the oil fill cap.
Looks the same as what the Positive Crank case Valve vents off!

 

[chill]

mmm, not really. I am aware of the lighter color of gunk issue with these motors and that is what disturbs me. It is black not tan or yellowee.

I will be removing the TB and =doing a cleanning job on it. Thanks.

 

[LibertyTC]

Buying used you hope they did regular oil changes and used quality filters.
Ever since I switched to Mobil 1 full synthetic me got no gunk under cap.
Check the PCV valve and replace it if it is gummed up.
Doing throttle body cleaning is good, do the IAC/TPS and ports while there too.

 

[chill]

Buying used you hope they did regular oil changes and used quality filters.
Ever since I switched to Mobil 1 full synthetic me got no gunk under cap.
Check the PCV valve and replace it if it is gummed up.
Doing throttle body cleaning is good, do the IAC/TPS and ports while there too.

Full synthetic could cause what is in the engine to get lose and foul the motor, Right?

 

[streetglideok]

No more then other oils would. Synthetic is more stable and more durable, and more consistant, doesnt mean it cleans better. How clean is the dipstick? Lots of times I see customers come in, and you can see oil sludge deposits on the dipstick partway up. Obviously the owner has gone too long for that oil between services. If it is oil sludge, may consider doing an oil "flush", to get the crude out, and keep the chain tensioners from gumming up, etc. Do an oil change, and leave the engine 1 qt low. Top it off with ATF. Run it for 20-30 min, drive it a short distance if you like, then change the oil and filter and fill it with whatever oil you run, in the weight it calls for, 5w30 in most cases. ATF is a geat cleaner, but isnt meant to run in the engine long term.

 

[ridenby]

Not so sure about ATF in engine,think I would just change oil/filter now,again in couple thou,then every 3000m after that. change air filter also.

 

[streetglideok]

ATF is a well known cleaner in the auto repair industry, before the days of BG engine flush, etc. I wouldnt use it in a diesel, and I dont suggest using it for more then needed for cleaning the engine, but it is good. Look out how well it cleans off your tools if you ever dropped a trans pan. Compare that with engine oil, and its striking. Clean engine oil will help keep an engine clean, but you need something with more detergents to get out the crude. Case study: Dakota 3.9L v6, very audible lifter tick in the engine. Verified somewhat dirty oil on dipstick, did a oil pressure reading(hot) with an external mechanical gauge to look for any obvious signs of problems. Nothing found unusual, so did oil change, added 1qt atf, rest regular oil, let it idle for 30 min. Came back, noise gone, and oil already getting really dark. Changed the oil and filter again with regular oil this time, she hasnt had a problem since. You wouldnt want to run any kind of flush for long in anything and this is no different. Im sure there is plenty on google to back up my years in the shop.