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Naturally Aspirated
Join Date: Aug 2004
Location: Minnesota
My Ride: 1992 Dodge Daytona
Engine: 2.5l I-4 super 60
Induct: Turbo
1/4: 0.000
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I myself have done some extensive work in rebuilding the Chrysler 2.7s with much success so far.
The number 1 gossip item regarding its failure is the water pump design, which is internal to the engine and driven by the timing chain. Well, you guessed it--possible coolant contamination. However, the water pump does incorporate a weep hole to allow coolant to drain outside the engine by the thermostat housing. Its not like these engines are guaranteed to fail as the water pump seal degrades slowly over time. Now, it would be possible for it to happen in such a situation (which I've seen many times) where the water pump bearings go out, so the pump no longer functions the way it should anymore, and since it has no bearings supporting the impeller shaft, the water pump seal isn't going to seal, and yah, the coolant gush is going to be more than the weep passage can flow, so it does go right into the engine oil. In the mean time, the engine is running with a misfire due to the cam timing going whacky, a CHECK ENGINE light, and timing chain/water pump noise that gets put off until the coolant contamination does take its toll, assuming it did not overheat and kill something else in the mean time.
Do note that the GM Quad 4 has essentially the same water pump setup as a chrysler 2.7. The pump is outside of the engine, but the chance of it leaking into the crankcase is the same, minus a gasket that could possibly leak one day. I don't hear anyone crabbing about the Quad 4 water pumps leaking coolant into the oil. Unless I haven't been listening enough.
Also, think you're 2.7l is rod knocking? The 2000+ engines have an updated timing chain tensioner design which likes to blow its O-ring that seals oil pressure behind it. When this happens, the tensioner can no longer do its job, and the primary timing chain rattles and makes a noise darn near identical to rod bearing failure. Wonder why that O-ring blows out? These engines produce 125+ PSI of oil pressure when cold at 6,000 RPM. Also, if this seal blows, oil pressure to the rest of the engine kinda takes a hit as well. If fixed in a reasonable amount of time (day or so) its no big deal. Let it go, and its very hard on the chain. First thing to do is pull the pan to look for debris. That'll tell you if you need a new engine or not.
The intake manifold and PCV valve placement between the LH and the JR cars iare identical. Gunk does tend to build up inside these manifolds, but I have never found a PCV valve to be plugged up, yet. HOWEVER, every one I've fixed/rebuilt had a deteriorated PCV hose. They either had large holes in the underside of them, or have totally collapsed. So, this can undoubtedly result in some kind of oil breakdown.
I'm not saying it does not happen, but I have never seen or heard of a camshaft seizing on a 2.7L yet. All the heads have been trouble-free. No cracks, no warping, etc. Water pumps sieze and snap the timing chain though. When the chain snaps, piston will meet valve unless you get lucky.
In my opinion, there is more than one contributing factor to the 2.7L failures.
1.) is the deteriorating PCV hose. It must have some kind of effect on the oil inside, and its probably not a positive effect. Proper visual maintenance will notice this.
2.) Ever run a 2.7l at high RPM with the front cover removed? You can watch the oil level in the pan drop substancially as RPMs increase. Upper end with 4 cams, 24 lash adjusters, oil pressure accumulators, two secondary timing chain tensioners, 100+ psi of oil pressure, there's a LOT of oil floating around in the heads of these things. You cannot run them without valve covers without shooting oil across the garage. Trust me, I've tried. Imagine Joe Schmoe who's never checked his oil in the last 4,000 miles runs it to 5500 RPM on a steep hill while 2.5 quarts low on oil with a pan design that doesn't have a sump for the oil pickup. HMMMM. Maintain your oil level.
3.) Neglect. All engines will sludge if you neglect them. You can walk through the junk yards and find engines of all genere sludged up. Usually caused by lack of maintenance and/or faulty PCV systems. Never have I found the oil pickup tube clogged full of sludge. Thats the cleanest part of these engines. All the supply passages are were clean and clear. The oil returns may have been restricted a bit, but not enough to be the root cause of oil starvation. Change the oil sometime in the next 10,000 miles and use good oil.
The 2.7L is a quiet engine. If its making any kind of noise, don't put it off. Get it checked by someone who doesn't just say the 2.7L is junk and you need a new engine. I'll save a $2700 engine by buying a $1.04 O-ring.
My last rebuild 2.7 has 5,000 miles on it now. I pulled the valve cover recently and inside there isn't the slightest indication sludge buildup. I use 10w30 conventional valvoline. Runs/sounds awesome. It better though. It needed $1850 in parts alone!! Yeeouch!
Anyways, </Rant>
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