TheSamba.com :: View topic - Piston ring wash-down?

Sat Nov 27, 2004 7:03 am

Ok all along I knew my motor was running rich,bought different jets to try to lean it out. I thought it helped,but guess not. So I took the car over to a guy who works on nothing but old Porsche's. After he did a compression test the results were scarry. The numbers were low,but said he thought that the compression was lowered due to the excess fuel being dumped into the cylinders. He used the term "Washed down". He then went on to say that if he cleaned them up he felt like the compression would rise back up and then he could readjust the carbs. He said he wants to clean it up and then do a leak down test and if it rised back up he would work on the carbs from there. Whats your thought on this? Also time wise how long should a leak down test take?

Sat Nov 27, 2004 8:56 am

compression test only give you a very vague indication engine condition. Your valves may not be sealing too well and that'll make your compression test result look grim and yes of coarse rings not sealing.

How old is your rings?? engine??? If your engine is relatively fresh then I'd say adjust your rich a/f mixture problem and drive the car for a while. You'll really have to dump major amount of fuel to wash the rings. When your engine is running are your eyes watering with the amount of HC's coming out of the tail pipe???

what engine?? carbs???

If your rings are washed down you'll need to replace them and re-hone your cylinders. Not that difficult but it does take time.

A leakdown test will indicate if the loss of pressure is from compression passing the rings or passing through the valve and valveseat area. Or even a possibility that the heads are leaking past the mating surfaces of the cylinder to head area.

leakdown should take around 45 minutes or so. Its just a pain in the ass to keep the engine from rotating when you apply shop air into the spark plug boss area. You must remove all 4 sparkplugs and use an adapter with a guage. More expensive accurate leakdown testers have 2 guages. This will show exactly where the leak is occuring.

I'm banking that the valves and valve seats are not sealing perfectly. Unless your engine is tired and you really dumped massive amounts of fuel down the combustion chamber and "washed the rings"

Sat Nov 27, 2004 9:13 am

The motor is newer 1914cc with dual 40 Dellortos--about 5 months old!
There has been the smell of gas in my oil,prolly from the stock fuel pump.
I changed the oil with a quickness,but untill I get an electric pump it will continue to do it. Getting back to the carbs,he thinks their dumping way to much gas and causing the wash out. Without having other jets to plug in could the carbs be adjusted to lean the problem out? No it won't make my eyes burn,but the plugs are full of black soot-aka-RICH.
Where to go from here?

Sat Nov 27, 2004 9:37 am

What jets are you running in your 40 dells???

If your stock fuel pump's diaphagm is leaking that may just be the cause of fuel contamination to the oil. OR your needle and seats are not sealing properly in the carbs and its dripping fuel down the carbs manifolds into the engine. Does your engine start immediately after its been sitting over night or does the fuel pump have to fill up your float bowls in your carbs???

What idle jets in your carbs??

Black soot?? or is that oil consumption black carbon?? You may just need to turn in your a/f mixture screw.

Sat Nov 27, 2004 10:53 am

either way you may have waited too long; the cylinders might have glazed up by now. change your oil, shoot a BIT of oil into the plug holes and do your carb. adjustments/ pump replacement; or whatever to solve the gas washing the rings. then if you're lucky the compression may come back up. it's the same problem when digifant vw's[ and i'm sure many other newer cars] crank but don't start- every time you crank the motor and it doesn't fire the injectors fill the cylinders with fuel which then washes the rings dry and voila- no compression.

Sat Nov 27, 2004 12:00 pm

The car starts fine after a night, 130 Main gas and 190 main air. These were the numbers CB performance to ld me to go with. I'd have to dig to get you the rest of the jetting numbers. The diaphrams are not fine -no tears. Could the heads also be getting loose making me lose compression?

Sun Nov 28, 2004 8:03 am

Combo of the heads maybe needing to be tightend a little and the washdown making the compression so low? So how does the process of cleaning work---take all plugs out,how much oil should I put into each,and I turn the motor over without the plugs in right? I'm guessing the oil is gonna spray out or no? Should I reclean the carbs first then move on to the oil pouring? Help-help-help!

Sun Nov 28, 2004 8:39 am

I am not a carb guy but I think your fuel pump is putting out too much fuel pressure for the kads. You need a regulator to reduce the pressure. I think they like really low pressure like less than 2 psi. If your mechanical pump is leaking from the diaphram, replace that pump with another mechanical, not an electrical pump.

Adjust the valves first and make sure the torque on your head bolts is at the Bentley spec second.

Third, if you put the oil in the cyclinders it is just a squirt (tablespoon?) from your oil squirt can. Take all of the pugs out, put in the squirt, run the starter, then you will put the plugs back it, get it warm (not hot) and then re-check the compression.

Dink with the carbs last. Like somebody else said, they might just be needing an adjustment.

If it were me I would take it to someone who has an Exhaust Gas Analyzer and knows what they are doing to have them dialed in the carbs correctly.

If you don't have the adjustment book on the kads, at least go over to the aj simms site (who I guess is the kad guru) and start reading. aircooled has some good reading on adjusting carbs and synchronizing dual carbs also.

Sun Nov 28, 2004 9:32 am

Randy the carbs are Dellortos and the Dellorto superformance book says they will work correct on about 3 1/2 lbs. So whats the max the stock pump puttin out? Going back to the cleanup...What type of oil do I want to use? The same as whats in my motor now? or 3in 1 or wd-40 type? Someone said something about using wd-40,but I would think that would break down too much of anything in there. Next to torque the heads does the motor have to come out? I've seen an article from an old vw trends where they did it in the car. I know the ones in back of the rockers I can get to ,but what about the ones on the top of the heads near the spark holes/manifolds? Could I just take the tins off to get to them? This is good I feel like I'm getting closer to knowing how to do this-any other help would be great---I may try this today if all the info is there.

Sun Nov 28, 2004 10:29 am

A squirt or two is all that's needed. Do that and whiz the engine over, without the plugs, a few times to distribute the oil. Otherwise you won't get a good leakdown reading. Those tests are a pain in the car but they will tell you where the problem is. A two gauge system will tell you the percentages of leakage. Anything over 8-10% leakage needs to be investigated. Bad rings will be evident with air leaking into the crankcase. You will be able to hear it. Along those lines, intake valve leakage will be heard in the intake tract and exhaust in the exhaust system. Loose heads will have leakage from the cylinder to head sealing area.
Does this engine puff smoke from the exhaust?

Sun Nov 28, 2004 10:35 am

Yes rich/black smoke but not pouring out...just lightly when you gas it.
So what type of oil to squrt in? What about the head retorque? Motor in the car can do?

Sun Nov 28, 2004 10:40 am

Use whatever you use in the crankcase. It's not a big deal.
Head torque depends on engine head stud size. Larger 10mm get about 22-23#, the smaller 8mm get 18-19#. No more than that.
It's a little tough in the car. You have to remove the rocker arms and cylinder overtin to get to all of them. Check the lower ones first. Those are pretty easy to do in the car. If they are loose, chances are so are the uppers.

Sun Nov 28, 2004 11:09 am

Your mechanic seems to know what he is doing, why not just stay with him?

Sun Nov 28, 2004 2:21 pm

Ok I tried it,The number 3 came back up to just about an 8bar-this is good! However the number 4 stayed the same pretty much only about 65 lbs there??? I may try that one again,maybe not enough oil or turns over. My number 3 has always given me some problem with the threading-think I may have crossthreaded it some time back. That could be giving me a shitty reading on the compression although I can't hear it leak and the plug does get tight,just don't get as many turns on it as the others.
Maybe a leakdown test should be in order,this would tell me if I need new rings right?

Sun Nov 28, 2004 4:44 pm

when you're checking the fuel pump, check everything: the height of the block it's mounted on, the lenght of the pushrod, open it to make sure the diaphram isn't torn. also check pressure and volume. have you checked the carb floats? . also you're compression did come up a little? see if it'll run, it may still come up a little more. of course 65 lbs. is a little low but maybe.

Sun Nov 28, 2004 4:51 pm

Oh don't get me wrong the car still runs,just nothing like it did before.
with 65lbs in the one cylinder it's like I'm running on 3 cylinders.
I do have 120lbs in the others...I just don't want to make it worse by driving it with the fuel in the oil eating my motor up. I gotta find the problem,fix it dump my oil and haul ass again :D
Thinking the leakdown test is a good idea...If it just needs new rings a fuel pump and a carb adjustment I'll be happy not to have to replace the pistons and all.