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how do you know when your engine needs a rebuild?
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Author:  Eatkinson [ Wed Apr 29, 2009 12:07 pm ]
Post subject:  how do you know when your engine needs a rebuild?
So I pulled my '63 Dart wagon out of the storage this past week.

Over a 10 year period, she's been started up a number of times (not enough certainly, but some). Oiled the cylinders and did some by-hand turning before I fired her up. She still runs pretty well, though there's a lot of sooty brown and blue exhaust when you gun the engine. CAVEAT: she had a tank of old bad gas (which is what she was running on in the attached video) which I proceeded to siphon out and replace with a tank of fresh and new. Now she runs pretty smoothly at idle.

I got her brakes working, put in additional transmission fluid, a new air cleaner, and away we went on some local driving around town. Even took her on some local highways and freeways at driving around 65mph. She did great.

Then we got back into town and sat at a stoplight, where her oil light flickered on at idle, sitting at a stoplight, and proceeded to flicker until I shifted into neutral or drove away. This was pretty much par for the course, when last I was driving her regularly. Under normal conditions, she does blow some blue exhaust, so I know there's oil burning where there shouldn't be.

I'm pretty sure she has been through one engine rebuild already (not under my ownership) though I will try to find out for sure. But she has 170K miles on her original engine. What I'd like to find out (and I know this is a very general question): How do you know when an engine needs to be rebuilt? What is the criteria? She runs fine right now, except for the oil light that comes on when she's warm. I know she has enough oil, so perhaps she just needs new rings. But she's definitely getting up there in terms of mileage.

I've never rebuilt, or had rebuilt a SS before, so I'd appreciate people's advice on this.

Here's a video of her running:

Image
Author:  Aggressive Ted [ Wed Apr 29, 2009 1:02 pm ]
Post subject: 
How does the compression test come out?
Can you post pressures for each cylinder?
Author:  Reed [ Wed Apr 29, 2009 1:07 pm ]
Post subject: 
Well, you definitely need to adjust the valves, and getting that A/C working again would be nice.

Put a mechanical oil pressure gauge on the motor and see where it is at when hot. Do a compression check. Do an oil change with a good (Napa Gold or equivalent) oil filter and some 5W-30 oil. You might just need a good tuneup and some valve stem seals.
Author:  Joshie225 [ Wed Apr 29, 2009 1:22 pm ]
Post subject: 
Low oil pressure, uneven or low compression and oil consumption are the main reasons for engine rebuild or overhaul. My Valiant's 225 uses oil and the cylinders have tapered wear. The head is fresh so I'm quite certain the oil is passing by the piston rings. You may be able to replace the oil pump if the pressure is a little low and new valve stem seals could stop the smoking, but if the compression is low or uneven (and the valves are lashed correctly) more extensive work is indicated.
Author:  wjajr [ Wed Apr 29, 2009 1:26 pm ]
Post subject: 
Well if you going to drive her a few hundred miles every ten years I wouldn't bother with a rebuild. However a lot of the maladies you describe may lessen with use. Letting any car sit for any length of time will cripple it seals dry, rings stick, valves become corroded and won't seal, carburetor becomes crusted with varnish, bla, bla, bla... You get my drift

I would drive it for a thousand EASY non hurried miles, and see how she is running. Firstly check compression, vacuum, adjust the valve lash, clean the carburetor or rebuild, blow out the fuel line, change oil & filter,flush the brake fluid, and flush cooling system & refill with new antifreeze now for a base line, and 300 or 400 miles down the road recheck compression, and roll on some more miles. If by the 1000 mile mark nothing has improved, it may be time to freshen things up.

As for low oil pressure at warm idle, the oil pressure regulator, part of the oil pump, (a little piston & spring combo) may be sticking from old crud & nasty oil. This can be easily cleaned per factory manual. A heavier grade of engine oil may help also after cleaning & no correction.

Once you get to thicker oil, still have a flickering oil light at idle, blue smoke under load, and low compression it is time to rebuild it.
Author:  coconuteater64 [ Wed Apr 29, 2009 2:19 pm ]
Post subject: 
My $0.02:
Adjust the valves, like Reed said. Then do a compression test and a cylinder leak-down test to see what the cylinders are like. As stated before, uneven compression between the cylinders could mean the rings have gone bye bye, or the valve seals, or the valve edges could be worn, or valve seats. Or the cylinders could be scarred.

If the compression checks out and the leak-down doesn't appear excessive, change the oil after running some Sea Foam through it. AVOID FRAM FILTERS!!

The oil light could just be a sensor. Mine went bad and bled oil all over the motor. replaced it and the idiot light went out. If the engine isn't knocking I would suspect the oil sensor is faulty.
Author:  Eatkinson [ Thu Apr 30, 2009 5:02 pm ]
Post subject: 
Thanks guys. All good suggestions. I just found out that to our (my's and the previous owner's) knowledge, the engine has not been rebuilt, so that's 170K miles on an engine that's not ever been apart. I'll have to be around the car again to test the cylinder compression, and yes, you're right, the valves certainly do need an adjustment. Will be lettin' you know the result!

Oh BTW cocoanuteater64, how do you perform a cylinder leak-down test?
Author:  coconuteater64 [ Thu Apr 30, 2009 7:00 pm ]
Post subject: 
A leak down test is similar to a compression test but instead of measuring pressure, it measures pressure loss. Yank the spark plugs and put the cylinder at TDC with the valves closed. There's a fitting that screws into the spark plug hole and hooks to an air hose with a gauge. Pump compressed air into the cylinder (80 psi or so) and unhook the hose and start the clock. Check again and the pressure will have dropped, even on a new motor. If it's only leaking 10% or less, it's in great condition. Up to 20% is pretty decent on a used motor like yours. More than that, start buying parts! Do this for each cylinder.

The cool thing about a leakdown test is that it tells you where the pressure is going. If you hear air coming out of the exhaust or intake, a valve is bad. Air coming out of the breather vent or PCV valve says the rings and/or pistons are shot, Air bubbling through the radiator (I take the cap off the radiator) means a head gasket is suspect.[/i]
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