Okay - how do I change the rings?

[Bostonian1976]

Unfortunately my truck now has so much blowby that it's undrivable. Oil splatters up on the firewall from the filler tube splatter, and it's a big mess. Taking off the filler tube cap and revving the engine yields a good amount of exhaust coming from the fill tube. what next? Compression is good, but per an earlier discussion on here someone said the oil in the cylinder could be giving a false reading. I really want to be able to drive my truck at speed again

[greenmeanie]

It's like any other engine so for a complete description your best just looking up something generic on the interweb.

Short answer is you'll be pulling the head off, the sump off and then pushing the pistons out the top of the block. At that time you'll want to have a good look at the cylinder bores for wear after giving them a bit of a clean. Any significant lip means you're looking at a rebore, oversize pistons and new rings. If there is no lip then you can get away with a hone. If doing it right you'll get the cylinders measured for wear and runout. Knowing the size of you're pistons you get the matching rings and the assembly is pretty much standard wrenching. Use only engine oil to lubricate the bores and run it on cheaper stuff for the first few hundred miles to help the rings break in.

Then shipfitter's disease sets in because if you have the big ends off then you might as well replace the bearings there, which then has you looking at the wear on the lands on the crankshaft.... .... and then you realise that you've just entered into a full bottom end rebuild. Yes it is more time, money and hassle but I believe in dealing with subassemblies rather than individual fixes.

Cheers
Gregor

[daveb]

what are the numbers to back up your statement that "compression is good."

please provide details as to how you conducted your compression test and what the results were.

rgrds
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Unfortunately my truck now has so much blowby that it's undrivable. Oil splatters up on the firewall from the filler tube splatter, and it's a big mess. Taking off the filler tube cap and revving the engine yields a good amount of exhaust coming from the fill tube. what next? Compression is good, but per an earlier discussion on here someone said the oil in the cylinder could be giving a false reading. I really want to be able to drive my truck at speed again

[Mercedesrover]

what are the numbers to back up your statement that "compression is good."

I was wondering the same thing. Good compression and terrible blow by don't really go hand in hand. Perhaps you've got a different problem than bad rings.

[SafeAirOne]

Workshop Procedure

Read section 12.17.01 and beyond at:

http://www.landrover.ee/est/files/manuals/cars/sIII/SIII_ROM_Part_2.pdf

(4MB PDF file)

[Bostonian1976]

I was wondering the same thing. Good compression and terrible blow by don't really go hand in hand. Perhaps you've got a different problem than bad rings.

I have to go look on my phone (saved the numbers on it) but it's between 135 and 140-some on each cylinder.

Procedure used:

Cranked started with compression tester in place (cranked 2-5 times)

what other problem could I have? Keep in mind this was sudden too....

[sven]

Compression testing is a good tool. But a leakdown test would be more accurate. I bought one from harbor freight. The gauge is kinda useless but you can use it to hear where the compression leaks are. I recently did a head on a 2.5 D90 motor, and with this tool I was able to figure out that the #4 intake valve was shot.

[Bostonian1976]

so - pardon my ignorance, but could my valves be causing this scenario?

[SafeAirOne]

so - pardon my ignorance, but could my valves be causing this scenario?

That depends---I don't have a 2.25 petrol in my rover, so I have to consult the photos on page 7 of the RN catalog. One shows a photo of an engine with the filler tube going down and entering the block below the cylinders. If that is your engine then no, the valves are NOT likely to be the problem. The exhaust is going the other way, getting past the pistons (via bad rings, a hole in the piston or a scored cylinder wall--all bad news) and blowing sump oil up through the filler tube. This will mean you'll have to pull the pistions out as greenmeanie indicated.

If your engine is like the one with the filler/breather mounted on top of the valve cover, then it is possible that bad valve(s)/guide(s) could be the issue.

On either-type engine, if it were me, the first thing I'd do is pull the spark plugs and look for the one(s) that are obviously bad (burned/eroded away or covered with oily goop or somehow different than all the rest).

Then if I had the oil filler on the valve cover-type engine, I'd pull the valve cover off and look at all the valves and guides, paying special attention to the exhaust valves/guides and even closer attention to the valves on the cylinder that I found the bad plug(s) on, if any. I think it would have to be a REALLY BAD leak to blow oil out through the filler on this type engine though (unless the valve leak was right below the filler hole).

There are a few more checks I'd make on this kind of engine, but they could be EXTREMELY messy if not properly executed, so I'll stop here for now...

Other than oil intrusion into the bad cylinder(s), I can't imagine a way to have good compression in all cylinders in any scenario. Sven is right, a leakdown tester is the best way to accurately tell what is going on. Of course you also need a compressor to use it.

[Tim Smith]

Mark,
I've got the same problem as you right now. Tons of blow by, not sure why.

I'll watch this thread to see what you find out, and if I find out what my problem is then I'll be sure to share. Too.

Cheers,
Tim

[scott]

why couldn't blow by be cause by bad valve(s)? if an exhaust valve(s) does not close completely pressure would build under the valve cover. that which can't vent through the valve beather cap because it's clogged would route down past the push rods to the the oil sump, right?

[SafeAirOne]

why couldn't blow by be cause by bad valve(s)? if an exhaust valve(s) does not close completely pressure would build under the valve cover. that which can't vent through the valve beather cap because it's clogged would route down past the push rods to the the oil sump, right?

Hmmm...I'm just running through the process you describe above. It is possible...the rocker compartment is connected to the oil sump by oil return journals. I just wonder of enough pressure would leak between the valve stems and guides instead of taking the path of least resistance (throught the exhaust manifold and out the exhaust system.

Easy enough to figure out by pulling the rocker cover and having a look-see....

The whole thing could also ba a bad head gasket, too.

[Mercedesrover]

There is, ah, some inaccurate information in this thread….

First of all, the area under the valve cover is for all intents and purposes the crankcase. It shares the same atmosphere. Pressure in the crankcase will also mean pressure in the area under the valve cover. It is linked together by large oil return galleys and is the same space.

Second, this isn’t a worn/leaky valve guide problem. The only real symptoms of bad valve guides/seals is oil being drawn into the portion of the intake system directly above the intake valve, being taken into the combustion chamber and burned as fuel resulting in blue smoke out the tailpipe, (especially after conditions of long, heavy intake vacuum such as coasting down a long hill), and the suspect cylinders fouling with carbon build up, evident with a blackened sparkplug. This problem will not affect compression nor cause any undue crankcase pressure.

Thirdly, this isn’t caused by a valve not seating properly either. If an intake valve fails to seat completely your symptoms will be popping back through the carburetor or a failure to run at all due to a lack of compression. The failure of an exhaust valve to fully seat will result in partial combustion outside the combustion chamber (past the unseated exhaust valve) and will quickly result in a burned valve, lack of compression and a miss-fire in that cylinder. This problem will not attribute to crankcase pressure either and will be easily noticeable with a compression check.

Pulling the valve cover will not allow you to determine anything about the condition of the valves. Even pulling the head will tell you very little about the condition of the valves. You will need to pull the head, cam and rocker assemblies and then the valves themselves to properly see what the guides and seats look like. Your problem, however, isn’t valve related so don’t worry about doing that.

What you need to do at this point is to get an accurate compression and leak-down test on this engine. You’re sure that it is running on all four cylinders and that it is not skipping, right? If this is a ring or a head gasket problem, these tests will tell you. There will be a large difference between one or two of the cylinders compared to the rest. Get a good tester, pull the coil wire and crank the engine over with the starter. You said in a previous post that this problem started all of a sudden. Broken rings could be the problem, though in this case worn ones wouldn’t.

You also didn’t mention that you’re burning oil. A bad head gasket that would allow exhaust gasses and compression into the crankcase would also allow engine oil into the combustion chamber under vacuum (intake stroke). That would be very obvious as well so I don't suspect a bad headgasket either.

I really think your problem is less dire than you fear. A burned out piston would certainly cause a miss in the engine and a presence of crankcase pressure so great you wouldn’t be able to run the engine at all. A broken ring could cause this problem but it’s really not that common. And if your compression/leak-down test doesn’t turn up anything significant, you can look to simpler problems.

I would first check that the PVC system is hooked up and operation properly. You mentioned that it’s been messed with. Find the proper hose routing diagram and hook it up properly.

I would also pull the valve cover and check the return galleys leading down into the lower section of the block. If they’re getting clogged up with gunk and not flowing properly it is possible to pool an excess of engine oil on top of the head to the point it will try to escape out of the breather cap. This problem will be especially bad during long high-RPM highway driving.

You might also want to compare what you think to be excessive crankcase pressure to another Land Rover engine without your problem. All engines have some crankcase pressure and some more than others. Perhaps your crankcase pressure is normal and the oil being forced out of the engine is from a different cause.

Good luck and keep up posted.

[I Leak Oil]

Bostonian,
Did you ever get the shims to put under the distributor flange? Just curious...
At AMD last year you had this problem but the truck wasn't burning oil if I recall, just spewing it out..I would think that if the rings were that bad it would also be sending smoke signals.
Jason T.

[graniterover]

Jason,

I was about to post the same thing as Jason. No way that oil in your engine compartment is 'blow by'. You have a bad seal or gasket somewhere. That oil was pouring out. Oil pressure line maybe (if you already fixed the distributor leak as Jason noted.)

Is the truck in Boston? I'll be down there on Wednesday afternoon, although I'll be in a suit and can't crawl under the truck.

I'll probably be driving around NH next weekend as well. If you're going to be around pm me.

Mark

Bostonian,
Did you ever get the shims to put under the distributor flange? Just curious...
At AMD last year you had this problem but the truck wasn't burning oil if I recall, just spewing it out..I would think that if the rings were that bad it would also be sending smoke signals.
Jason T.