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2000 2.7 pistons and rings?

677 views 3 replies 3 participants last post by  case930man 
#1 ·
History of car. Purchased as sludge monster with broken timing chain and bent intake valves at 78k. Put back together and it used oil for 30k, about a quart every 500 miles. Crankshaft gear came lose and wore the crank so I glued on a new gear with Loctite high strength and put new alignment pin in crank. Started but ran rough and was misfiring a lot. Checked timing and it was correct. Tach was jumping so I tried a new crank sensor and that was the problem but now it has a ton of blowby. I must have damaged the rings to the point of no return. Smokes bad out of oil fill, PVC hose and breather when warm and idles slightly rough. If I take it out for a spin I get oil out of the dipstick tube at bottom from the blowby.

With all the new parts including copper brake lines, etc., I am going to try some rings and possibly pistons and rod bearings. I will do a compression test and leak down before disassembly.

I am seeing some pistons/rings on Ebay called NPR and wondering if anyone has had luck with these or what do you recommend? Should I replace the rod bearings? Maybe check oil pressure and if low then replace rod bearings? Not planning on doing crank unless those can be done in the car? I did replace oil pump also at 78k. If cylinders are wore beyond standard size I think I am going to junk it. I should have done the rings when I had the heads off the first time.
 
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#2 ·
You may be right, but although yours has a special history, it’s very rare for rings to go bad in these engines.

What is common is PCV issues and bad valve stem seals. With your saying oil comes out of the dipstick tube, my bet would be on something in the PCV system - usually a dirty/clogged PCV valve - or - a defective PCV valve. Chrysler has put out some PCV valves that had a defect that would cause the valve to mechanically latch itself closed (I got 2 of them). That causes the crankcase to pressurize with people reporting oil coming out the dipstick tube and other places. I realize that bad rings also pressurize the crankcase from excess blowby, but my bet would be on PCV problem.

Here’s a thread I did in the PCV valve defect (sorry the photo links no longer work): https://www.dodgeintrepid.net/18-ge...51-alert-check-oem-pcv-valve-design-flaw.html

To rule that out, I would try an aftermarket PCV valve, but also check your PCV and crankcase breather hoses for clogs or other problems.

Bad valve stem seals would cause high oil usage and billows of smoke out the exhaust under certain conditions, but would not cause pressurized crankcase.

Disclaimer: You could have bad rings (but I would first rule out the simple things). :)
 
#3 · (Edited)
Check what Peva said to do above^^

If not that;

I recommend a full rebuild;

Not sure what has been done so far or how much sludge remains; but if you are just tearing it down over and over again to do one thing at a time, you are wasting all kinds of time and money.

If you cant do that, sell it/junk it, trust me, it will cost you much more piecing it together and trying to do it in the car.

The rotating assembly in the 2.7 (pistons/rods/crank) is very solid and it is very rare for there to be an issue with them; unless it was caused by something else----ie sludge, leaky water pump/poor maintenance;

Normally if excessive sludge is present and the engine is worked on internally, but not rebuilt completely and cleaned out properly; generally that sludge is loosened up and given the opportunity to travel thru the engine in the oil, and destroy the bearings, oil pump, and cause excessive wear on the cylinders and pistons;

2.7's can be very tough but if they are allowed to get the sludge disease the best option is to rebuild them. Otherwise you'll be piecing it together for months and will be very frustrated with the amount of money you'll spend.

As far as the aftermarket engine parts most seem to be OK; but there are parts such as the water pump, and timing tensioner that must be replaced with the updated OEM parts, as the aftermarket does not make them with the updates as of yet. Remember you get what you pay for and there is alot of garbage parts out there, especially online. If its cheap, its likely crap.

New engine time.
 
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#4 ·
The crank sensor backfiring broke two of the pistons. Compression was 60 in those two pistons and 140 in the other 4. I was hoping someone had recommendation for some of the new pistons on ebay. I may just go with two used OEM as the pistons still look very good. Rod bearings had between 0.001 and 0.0015 of clearance but I think I will replace those also. These motors are tough. Cylinders look excellent for a motor that has been through hell. Sludged up to snap timing chain. Water pump was fine. These motors run too hot and that is the main issue. Cooling system stinks. Water pump design stinks and that main tensioner stinks. I think I will get another 100k out of this thing easily. I have 5 of these things now. Two running, one about to be running and two with engine damage. One bent valves as owner messed up timing trying to change water pump and one at 55k with frozen motor. That is my long term future ride, if the other ones ever die, with a nice rust free Iowa body. Here in MN rust kills these things before the motor dies. My sister bought one of these new in 2000 and she left it to me. I always took care of it for her and used Mobil 1. That is how I got started on these things. That one is still going but WP dumped coolant into oil at 126k at the gas station. I shut it off right away. Runs perfect with new pump and timing kit.
 
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