Rebuild questions

[Darren94]

So, i recently picked up a 98 B2500 with 179k on the ticker for $2000 which at the time of purchase seemed good because it run really well and was very clean inside and out. But, after a week or two of reading here and replacing parts trying to cure the rough idle and tendency to bog down while taking off in first (when motor is cold), i did a compression test. The numbers were

First try (cylinder by cylinder, no WOT): 75-87-172-177
Second try with all 4 plugs removed and at WOT: 96-90-215-210
Third try with oil added to the low cylinders: 217-240-215-210
Fourth try less than one min after third try: 122-137-215-210

Through the help of others that replied to my post, it seems to be clear that i need to re-ring it even though it runs really strong minus the the problems above.

My question is: if i decide to re ring it what else should i replace while i have it apart. Also, what to the re-ring kits usually come with??

I am either going to drive it until it dies or go ahead and fix it but, if i fix it i want to do it right. What would you recommend?

 

[Doodlebug]

If you are going that far into it and has that many miles on it, you should just rebuild it. Chances are that the bearings are worn and head needs work to. Do yourself a favor and replace all your fluids if you plan on keeping it.

 

[Will]

First, you can just drive it.

Second, you can tear it down and keep your mind open. Mike the cylinders and see how bad they are--shape and dimension-wise. If they aren't that bad, scrub them with emery cloth and throw some rings in. If the two do need bored, leave the other two alone. Over-sized pistons are the same weight as standard ones. The displacement increase is infinitely small and doesn't matter. This is what the service manual says to do, anyway. Don't throw away good parts and don't machine away good metal.

There are any number of things that could be causing low compression. Doing the test, have all the plugs out, hold the throttle wide open, crank them all the same number of times. I do 4 cranks. It looks like you've done the test enough to prove there are two reading low, and that it seems to be the rings. Do you have an air compressor that will attach to the hose on your compression gauge? I like to get that going and roll the engine around by hand and listen with the oil fill off. You'll hear the difference between the whipped rings and the good ones.

The only disturbing thing about your engine is that two are so good and two are so bad. I like a nice burned exhaust valve if I find a low cylinder. Two, together? I'm thinking head gasket and it's leaking between them. The compressor test will show that because the air will escape through the adjacent cylinder and you won't hear it unusually loud in the crankcase on those two.

It's coming apart, so mike the bearing journals and see if some new, standard bearings will work out. I think they will.

Remember--don't throw away good parts and don't fix anything that isn't broken. When it's apart, study everything and find the problem and fix only the problem. This is the key to a happy life.

 

[scotts90ranger]

that re ring kit I led you to had a head gasket, rings, valve stem seals, bearings and a few other gaskets.

I'm with Will, if you tear it apart only replace what's needed (but if you have new bearings, use them). I would change the front and rear seals along with any other wear parts that are hard to get to when the engine is in the truck.

 

[Sunk]

I'd just drive it for a while and see it's the root of the problem becomes more obvious. Mine idles rough when cold, I'm pretty good at 2-footin it now.

 

[Darren94]

Thanks for the help guys. I have a good friend who is returning from a 2 year stay overseas as a military contractor and he is a Toyota Master certified tech. I intend on having him help with my evaluation of the truck and make recommendations on what to do from here.

On a side note, are there any other tests/procedures i can perform in the mean time just to get any additional helpful results? I would like to use my air compressor and push air in as recommend above but, is there a write up somewhere on how to do it right? I don't want to spend any more money than needed on this and if the low compression is caused by the head or head gasket and not the rings, i would rather leave the bottom end alone and just fix the problems on the top end.

 

[rrbrian222]

Not being a mechanic, I like to watch youtube videos on car repair topics and learn about how certain things are done by the professionals. One test that you could do yourself, especially since you know how to test for cylinder compression is a leak down test (actually I'd suggest just using the technique Will suggested with the air compressor, kind of a poor-man's leak down test, lol)


Here's a video that explains how to do it and what to listen and look for while performing the test (fast forward to the 19min. point for the air compressor short cut):

 

[Will]

On a side note, are there any other tests/procedures i can perform in the mean time just to get any additional helpful results? I would like to use my air compressor and push air in as recommend above but, is there a write up somewhere on how to do it right? I don't want to spend any more money than needed on this and if the low compression is caused by the head or head gasket and not the rings, i would rather leave the bottom end alone and just fix the problems on the top end.

Keep driving it and you'll get more helpful results. Nothing ever gets better.

The air-leak test, I told how to do it right. Any decent compression tester has a standard quick-change coupling on the gauge which allows you to pop the gauge off and snap an air hose onto it.

Get a new gauge if yours doesn't. If you have a really bad gauge where you have a rubber thing you have to jam in the plug hole instead of threads, throw your test results out. When you buy a gauge, make sure there is a quick coupling on it and that there are threads for the sparkplug hole.

The rest of it is feel. There is no digital readout. Your motor is a pump. You are interested in how its sealing. You use your ears and you compare the cylinders to each other. It takes a little bit of feel, but nothing that is a challenge for the human body.

In the past before lasers and shit--machinists that did the most intricate work used feel-boards to judge when they had achieved the correct surface. The boards were machined to a certain tolerance and they would feel their work, and then feel the board to see if their work matched. Using a feeler gauge is no different. Getting the right feel on a feeler gauge is a matter of human touch. A snap gauge for checking the bore, using a micrometer--it's all having the right touch.

The digital age ends when you get into the reciprocating assembly. You are going to take that motor apart and use touch to determine its condition. Your eyeballs, the feel of the journals under the pads of your fingers--these are important things. There is no procedure--it's up to you. If your buddy is a real mechanic, he's going to use his senses as well.

You have to understand how it works, figure out what it is doing and compare that to what it should be doing, and use your senses, aided by your tools and instruments to decide why it's doing what it shouldn't be doing. That's being a mechanic. My 11 year-old can follow directions.