Engine that's been sitting

[RunninWild]

Hey guys I just grabbed an aaz. The seller says he bought it off a guy and has had it sitting for over 2 years. I'm unsure of how long it was sitting before then. Anyways the crank spins freely by hand. The timing belt is intact and there is no physically obvious damage. After squirting a bit of oil in the intake and spinning the crank (by hand) a few rotations I was starting to feel a bit of resistance on possibly 1 cylinder. Is it normal for the Engine to loose all compression when sitting for so long? I known the rings need oil to seal properly and I'm just worried I bought a dud. It's supposedly low mileage with only 180,000km on it.

[ORCoaster]

Dud?   Think where is that 23 to 1 compression going to come from if you can spin it by hand without resistance.  You may have rings that could be worn or not flexing out to the cylinder walls.  That is somewhat unlikely.  I would be pulling the head and confirming the piston size, the cylinder diameter and the condition of those rings.  There may also be valves that are not functioning well in the head.  Only a pull apart will solve your unknowns.

[RunninWild]

I've done a bit of googling and I've found a few forum posts with similar stories. According to them the rings can get stuck in the pistons and after they get oiled they should start to seal again. I'm fairly skeptical but the one guy said he had 40+/-psi in each cylinder which went up to 120+/-psi and then up to 160+/-psi (was a gas engine).

I've torn off all the accessories off the Engine I'm not using as well as the turbo and exhaust manifold. Plan is to pour a bit of oil down the valves and turn it over by hand a few times then let it soak in for a few days.

The guy I got it from seemed like a honest person and he said he had no reason to not trust the guy he got it from. I know that doesn't mean much but I'm giving him the benefit of the doubt.

I also noticed when spinning it by hand there was literally no resistance the first few rotations after a bit of oil got in it started building a bit of compression on the one cylinder and was enough that I could hear it leaking out the exhaust valve as I kept spinning it. I'm hoping for the best. The engine is clean enough for me to think it's not old enough to be completely worn. I'll try it out and if necessary I'll pull the head.

Can anything be told by pulling the oil pan? I can't afford a head gasket right now...

[Dakotakid]

No not really.
Let's just say....that if you go visit either of the two previous owners....and you drop your pencil on the floor.....don't bother to pick it up...go buy another pencil.

You just got taken to the cleaners. If you weren't a mechanic last week......you will be soon. You will have to start from scratch. Or, less than scratch. Either way, it sure looks like you need to start from the crank--out.

Sorry....sugar-coating will do you no good.

[RunninWild]

So there is no way the Engine could dry out and temporarily loose compression from sitting for  years?

Here is a forum post that kind of reinforces what the seller said. The guy I got it from is the head mechanic from bc hydro.http://www.bimmerforums.com/forum/showthread.php?1631083-E36-low-compression-after-sitting

Summary of the post

Short Version:
Car wouldn't start after sitting over the winter. Checked for fuel and spark but had low compression. Added small amount of oil to spark plug holes and compression improved and car started. What is wrong with my engine?
So, I was confident I had spark and fuel and proceeded to do a compression test. The compression test was performed with all of the plugs removed on a cold engine with the throttle body wide open. Here are the numbers from the front of the car to the rear:
55
35
30
66
57
45
I then added a quarter ounce of oil to each cylinder, ran another compression test and achieved the numbers below.
110
89
89
179
169
196
I did another compression test today after letting the engine warm up. The numbers look pretty good, so maybe all is well.

204
220
211
219
220
218

Buddy said he would give me my money back if it didn't work, I picked it up from his work and he has a job that he could probably get in some trouble if he was ripping people off out of their business. I doubt he would intentionally sell a scrap engine. Wether the previous owner before him ripped him off is another story.

Would you guys even bother going through the hassle of trying to install this or should I just bring it back to him?

[RunninWild]

Can the valves stick?

[RunninWild]

I just had another chance to play with the Engine. I poured a cap full of oil down each exhaust valve and rotated the crank about 20 times and it's gaining compression. The 1 cylinder Is at The point where I'm having a hard time even turning it with my 3/8 ratchet and the others all feel fairly comparable to my current 1.6. I think it just needs to be run a bit and lubed up. I'm going to install it and hope for the best

Also when I pulled the exhaust manifold I noticed one of the valves was wet with oil. Is that a valve stem seal issue? I have a new head I was planning on swapping in anyways just wanted to get on the road with this one before I went through the trouble of ripping it apart.

Also when i was spinning it by hand i was just turning the flywheel with 2 hands. I didn't clue into the amount of leverage I had on the crank spinning it like that.

[ORCoaster]

From my experiences of nearly 40 years of working wrenches and engines I do know that putting oil in the cylinders increases the compression.  I puts a coating on the cylinder walls and fills in some of the gap.  Now will it make the rings loosen up and do their job?  Hmmm, I don't think so, at least not in a reliable manner. 

Why do I say that?  Well the last engine I took apart was the 1.6L in my current 1981 Rabbit.  It was becoming hard to start and the numbers were in the 280 to 300 range.  Not really a problem on a summers day but 30 degrees and cloudy was a prayer and start number.  So I pulled the head.  I did have some rings in pieces but mostly they were stuck into the grooves and I really had a hard time getting them out.  And this was on a running engine mind you.  So in my life I have seen the diesels hold them real tight because of the carbon build up and then on a gasser they are stiffly in there but with a bit of lube they do get to freeing up.

The difference is in the pressure you need to fire effectively on the diesel and the type of burning going on in the cylinder.  When you pull a spark plug and it is all black and nasty looking a simple brushing with a soft brass brush will generally clean them up.  Try that on the bottom of the heat shield or the injector of a diesel.  It won't touch it.  You need to get a steel bristle brush and maybe even, Lord don't strike me here, a scraper on them. 

So you can go through the time and energy to install the engine but I would fear doing more damage than good by firing it up and running some hardened carbon against the cylinder walls.  That will surely bring a lack of compression to that cylinder.  And if you don't think a solid piece of carbon will cut steel, well think of low grade diamonds.  Or carbide. 

My advice, don't do it.  You may very well have a good engine so why mess it up.  Yes, popping the top will cost a gasket and potentially new headbolts.  You are talking less than 50 bucks!  Are you willing to toast an engine two guys are telling you is fine for the lack of looking. 

You asked about pulling the bottom off.  Well You can at least get a look up under the pistons doing that.  Skirt looking, check for existing lines and piston wobble at the bottom end.  If the rings are stuck to the piston then you should be able to grab the rod and get the piston to wiggle in the cylinder.  You won't be able to get much oil on those lower rings so perhaps oiling from the bottom might help.

That's what I would be doing.  Is this engine on a bench or a stand?  for the work you want to do you want an engine stand so you can get around it without having to fight with it. 
 

[RunninWild]

I get what your saying but I don't think this is a carbon buildup issue from old age, but more of a 2+ years drying out in a heated garage issue.

How long do you think it would take for the oil I poured in the cylinders to leak past the rings? If I let it sit for a few days and it still has a lot of resistance would it be safe to assume it's good or that it's still wet compression? Or would it take a long time for it to drain?

If I pull the head how far would I have to get into this thing? Would I need to pull the pistons and inspect each ring or would a visual inspection of the cylinders be sufficient? I don't have a torque wrench or any measuring tools and I just got laid off and spending $300+ on tools at the moment isn't possible.

Also please keep in mind when I said it had no resistance I was turning the flywheel by hand. When i used a wrench  on the crank it was a lot easier to feel resistance. Even when it was at the point of me pulling the wrench really hard to turn it I was able to spin the flywheel fairly easily. I think my original statement of it Having no resistance and no compression was wrong.

[RabbitJockey]

i don't think anyones accusing anything but this is the original ad, said engine feels like it has low compression, but was supposed to run when pulled, if you want to save a click.

http://vwdiesel.net/forum/index.php/topic,36289.0.html

it sounds like you might be getting lucky though with the oil, i'd try atf over oil because of the extra detergent quality

[ORCoaster]

Ok, let's say the rings are just not doing their job.  I would assume that they may have carbon build up on them from when the engine was running.  Any idea on miles on the engine for an estimate? 

If you pour oil from the top there is only one gap in the ring where it can get down to the next once the top ring is sealed.  Not likely to happen as this was a running engine so the gap is probably filled up by now.  Oil can run down the cylinder walls if all rings are not sealing in the first place.  I really have no basis for guessing how fast the oil will take to leak to a lower position on the cylinder walls.  Setting up the engine and pulling the oil pan would allow you to see or place some paper towels under each cylinder to see if oil was dripping out the bottom.

If you pulled the head you would be half way home.  Pull the oil pan and release the pistons from the crank and you are 90 percent done.  That will allow you to pull, inspect, measure and determine the need for new rings, new piston size and the potential for just honing or a full bore of the cylinders to meet the new piston diameter.  If all you need is to clean the current pistons and hone the cylinders you only have to invest in a new set of rings.  That is easy to afford, go Gotez rings.  You can rent tools like the wrench, the hone, ring cleaner and the big problem would be timing the beast.  I don't ever see those tools for rent.  Who owns a 30 year old engine anyway?  Well, we do!  By rent I really mean borrow.  Most auto places charge you for the tool and if you bring it back in time they refund all your money.  So the use of the tools is free.  They will make their money on the parts you buy.  Unless you buy them from someone else.  Which is what most of us do. 

Ok, so it does have resistance when turning the crank with a wrench like normal.  I think I would continue to use the flywheel as it is easier on the arms. 

Hope that helps,  and if you are laid off there is no reason to lay around.  Get to work on looking at it.  Generally I have time or money but neither at the same time.  So, figure out what you need, the cost, where to get the parts cheapest and set yourself up for doing a little or all of it at one time.  You don't need this engine tomorrow do you? 


Good catch on the ATF.  Penetrates better.
 

[RabbitJockey]

I'm just assuming this was the one I sold, I think mileage was around 220k and 40k on rebuilt head, as I was told by the person I got it from

[fatmobile]

Depending on how easily it turns,.. it sounds like the pistons hit the valves. Goes around real easy then, ha.
 Maybe pull the valve cover and check out the lifters.

[RunninWild]

No that's not the Engine. I got it off of craigslist locally.
Was told it had 180,000km on it (somewhere around 100k miles). I was never informed of any low compression or issues with it other then it ran great when it was pulled according to the original seller.

When I say it's hard to turn now I'm fighting compression not valves. Once I get passed the peak of the resistance I hear a gushing noise from the exhaust valves and can see a bit of oil shooting out from where I poured it in.

I really think it's good. I'll pull the oil pan, because I was planning on replacing it with a new one (different drain location) and have a look up the cylinders and see if anything obvious stands out to me. But im going to go ahead and just swap it in this weekend. I really think I was overreacting and that it's fine.

There isn't a huge rush but my truck hasn't been on the road in almost a year and camping weather is approaching fast. I just want to drive it again 😢

[RabbitJockey]

thats funny the story matched up a lot with period that it sat and stuff with one i just sold about 2 weeks ago haha