I bought my 2002, 2wd Durango with the 4.7 liter engine back in 07 (SXT Package). I have loved it from day one. After purchasing a mechanic friend told me about the sludge buildup issue. after research i decided to flush the oil system... Added the sea foam, let it idle for 30 mins, drained the oil. Swapped it with full Synthetic, drove about 30 miles, repeated the sea foam and drained. re-filled it again with full Synthetic. I change my oil myself, usually every 2500 miles, never more than 3000. The truck runs like a champ with 160k miles. Untill yesterday...

While driving to Austin texas from houston, i stopped for gas... all was well, i fueled up, and drove off... I hadnt made it out of the little town of Giddings before i lost throttle response and my truck started bogging down the check engine light started flashing. i pulled over and it promptly died.

I popped the hood, checked fluid levels, all looked normal. i restarted it, and was able to limp it a mile down the road to autozone.

Diagnostic check said it was a "Random Misfire" Error code P0300. I bought a new coil and tried with every cyl. no change... a guy that had a durango pulled up and was asking the issue, i explained the situation. he said he has the same code, and it was the CPS (Camshaft position sensor) i replaced the 30 dollar sensor and it did run better, but still bogging down. (when i pulled the sensor it was covered with a thick, pudding like consistancy grey grease, or oil that was sludged'. that concerned me a bit due to my strict oil change habits, and quality oil.)

Scanned it again, came back as a TPS Sensor code, Replaced that, cleared the code, and it came back. swapped with another new TPS sensor, same thing.

By now im frustrated, about 100 miles away from home, none of my tools, and no internet access beyond my cell phone. so i take it to the auto shop next door.

HIS scan says it misfiring on 3 cylinders, 1, 3 and 5 i believe. so he compression tests them, 40-90 PSI on the bad cylinders and 120's on the other 5. he tells me i need a new motor, thats all there is to it. im reluctant to shell out the 4-5k he wanted in a BFE town to fix it. i call the same mechanic friend, he tells me to replace the spark plugs and to limp it back to houston if able.

3 hours later i get back to my house. Now im looking for input and advice. Im a DIY kinda guy, and i have a moderate understanding of engine mechanics... What can i do?


This just in...

Started tearing the engine down this morning, just got the Valve cover off and i saw this right away... (Pic) looks like the timing chain came off the camshaft gear... how would that happen? it obviously ate into the camshaft a little bit... so, new cam, new chain, new cam gears, new gaskets.

Now my questions are #1 wouldnt this explain the low of compression in the 3 cylinders, the cylinders were stair stepped in pressure... 42/67/91psi... if the valves were open at various levels wouldnt this be the obvious culprit?

and #2 would fuel mixing with my synthetic oil cause it to turn milky? i know water does this, but what about gasoline?

any help would be appreciated!

 

ok the sludge issues are a myth, a properly maintained engine will not sludge up therefor sludge is (ALWAYS) a maintenance issue (specifically lack of)


i would agree that you need a new timing chain kit (a good kit will include all 3 chains and all the gears) depending on how deep the scrapes/gouges are you may be able to reuse the camshaft itself, if you are uncomfortable with that then go ahead and replace it, new parts seldom hurt anything.


have you drained your oil that you say it looks milky??? the build up in the filler cap is considered normal on the 4.7 (it is often referred to as 'snot') and is not harmful to the engine, it is simply caused by moisture not being fully boiled out of the system. your 2500 mile oil changes are overkill IMO, i do 5k miles on a change with my 4.7 and that is still overkill according the owners manual (i believe it says 7500 miles), gas in the oil is also something that happens pretty regularly with any reciprocating piston designed engine and iv never heard of gas causing the oil to get milky, coolant in the oil will do this, but not gas.

i would also like to point out that from your picture there is 0 sludge in your engine!!!!!!!!

 

#1 sharp,that's a clean engine...,milky oil usually coolant,sumtimes air from cavitation but it will clear after it settles. If the oil hasn't been dumped check the level and see if it's higher than normal.Indicator something got in and added volume.Might have a head gasket or timing cover that leaked coolant in,it would be apt to smell like gas if it was a fuel leak ...chain tensioner prolly failed and caused the chain to jump...look for bent valves and/or damaged pistons...I don't see any rub marks on the chain in that pic,have me thinking one of the tensioners....

 

Thanks for the input guys! i really appreciate it! I have drained the oil, and it was milky. but is smells like fuel as well, not like straight fuel, but you can smell it... this is a little past what i normaly deal with!

 

look close at the pic. the guides are DONE! no rub strip left. whatever sprays oil on the chain(not sure yet what does it) is restricted somehow. and that is not a clean motor, pretty sludge free yes but not clean, i have 2 4.7s sitting in my yard one with 132,xxx miles and one with 90,xxx miles. both if you pull the valve covers look like clean virgin alluminum other then the transluscent syrup color of oil coating everything.

pull the oil pan, it will need to come out to clean out the timing guide bits and metal filings from the guide. once you do check the pickup screen to see if its pluged up. pull the cam and do a leak down test before you pull the head theres a very slight chance nothing bent but a huge likely hood you have 3 or 4 bent intake valves on that head.

that kind of miles seems to be middle of the range for timing chain issues based on what ive seen listed on craigslist needing timing chains. based on when ive seen people having issues with timing chain I would recomend anyone with a 4.7 around 120,xxx miles or more pull the timing cover to inspect and replace as needed before failure.

you pretty much reach the point where you have to decide should you spend a little more and freshen it up now or put it back together. cylinder wear seems to be good on these, have one with same miles as yours totally sludged up(guide worse then yours, it was in multiple peices) but no ridge at all in the bores so it could just get boiled the clean the oil passages and light honing for new piston rings.

 

I had to save the pic and open it in photo shop to see the color...I see it though,varnished. I can also see the wear you're talking about under the chain,that guide is history,knawed right through it.
There are oil supply tubes that feed the chain,they were talked about in another thread.With the guide being that gone I bet they are clogged,at least restricted...after this I'm pulling my covers back off and looking again,I gotta run back through the PO's tune anyway....
EDIT;question on that...oil varnishing like that,enough to coat the top end entirely,that's caused by a weak or bad PCV right and/or blowby contaminating the oil?

 

its not really a bad thing with most engines, most engines I have worked on before look like that. the 4.7 just seems to be more problematic when with any build up. since I am now pulling my sludged up bad timing chain 4.7 out I plan to disect it more carefully and see if any oil passages are actually plugged, i'll try to get some pics of the sludge in the heads to give you an idea of what was still running till 268,xxx km.

I personally think the problem is you really should pull the timing cover at a certan point and inspect. theres is specs in my haynes manual on max guide wear as well as max tension extension to determine if you need a complete kit. luck you down south that stuff can be found much cheaper then here in canada.

if you want to get a look at one of the guides a little better then pulling the valve cover lets you do then pull off the oil filler and have a look through that hole, theres also a plastic cover behind the power steering you can look through but be carefull getting it out(have to push it out from inside).

 

That's what I know of it,it's normal to an extent,excessive is a prob though.Didn't know about the plug,FSM calls it an access hole..TY. Thought I'de only get a look thru the filler so only 1 side(unless a cover pull).I've had some odd tappet type noise once before so like I said,covers off again,gonna look. try to avoid what brandon's going thru.Master tech tipped me off to the timing cover issues and the need to keep clean fresh a/f in 4.7's(thread about overheating and pressure in the cooling sys) so I know I'm up against a pull there eventually too.Using a haynes instead of FSM? I thought they were a no no?

 

either side is only going to let you look at the top end of the guide from the side, just give another veiw. after I spent working on my new engine I spent some time looking to see how the chain is lubed. theres is a VERY TINY hole in the tensioner housing next to the tensioner piston, and when I say tiny im guessing its .020" or smaller, it shoots oil through the middle of the tensioner arm to hit the chain. both the holes on mine are plugged but the one for the left chain is worse. the left tension has 2 oil feed holes on it, one to feed the piston and one to feed the sprayer, the right tensioner has one oil feed hole in it and I would guess feeds the sprayer internally, i'll disect both and drop them in a bucket of carb cleaner so I can see it better. they shoudl have just plumbed an oil passage to hit the chain under the valve cover instead of relying on a sprayer built into the tensioner.

I bet if you pull the tensioners you fill find junk behind them and the sprayer holes plugged.


theres nothing wrong with a haynes or chilton if your not a complete newb to fixing cars. if you are the kind of person that has to follow the instructions step by step then I wouldn't recomend you use a haynes or chilton because sometimes the steps make no sense or they forgot something. read as reference material and for specs because specs are normally correct in them. if I come across a FSM for the right price i'll buy one.

the worst part of this is that trying to clean your engine with products such as seafoam is probally the worst thing you could do to an engine like this with chain guides and sprayers, sure some junk left but the junk in the oil passages feeding the tensioners can't get out of the tensioners. only thing that could have helped would be a higher detergent oil that will keep breaking stuff down while you drive not just flush it once. theres also the old trick of half a litre of ATF in the oil the clean, but im starting to think that also might be dangerous with this engine. hrmm, more thinking.

 

we have fsm in pdf for available for download for free from the faq thread on this board.