Hi all,

I have a used and build engine with Arias 8.6:1 pistons and Eagle forged rods. It's been sitting in my garage for a little while, almost two years in fact. I soon want to drop it in and did a leakdown test on it. Four cylinders turned out with low leakage, two with moderate leakage. The leaks are always through the intake valve it seems. Should I be concerned? Does the fact that the engine has been sitting for several months affect the readings? Should I still consider to drop it in?

Thanks for any insights,

 

the valves might be open during test,could also be going past the rings.as motors sit oil drains back and provides extra clearance.plus your testing a cold motor,not a very efficient test.you can put a squirt of oil in the spark plug hole and see if your readings improve.is the intake on the motor?

 

Thanks! I tried to set up the pistons so that they're just a few degrees before TDC. All valves should be closed. I'll try to add a bit of oil in the cylinders to see if that make a difference. The intake is NOT on the car and I realize that a cold engine will leak more than a warm engine, that makes sense.

Thanks!

 

TDC of the compression stroke or the TDC of the exhaust stroke. if you are on the 4th stroke of the cycle, the valves won't be closed! you'll want to make sure that you are on the 2nd stroke (compression) of the cycle for each cylinder.

 

easiest way to tell is to stick a long rod down the spark plug hole and turn the engine until the rod reaches its highest point then do the leak down on that cylinder

 

could have a little crud build up from sitting with the intake valves open on the valve/seats that are holding the valves open. The question is waht the motor in goot shape before yu took it out?

 

that doesnt account for overlap

 

stock valve springs or aftermarket?

 

no but it helps eliminate some of the guesswork

 

i like to pull a valve cover an put fingers on the buckets,the first couple you may have to fiddle,but after that you can feel where the sweet spot is.

 

I would not expect a perfect seal from an engine sitting for 2 years. What are the actual leakdown %'s you are seeing?

 

you won't have any overlap if you are at the top of the compression stroke!

 

also depends on which hole you put the rod in, but doesnt it always.

 

+1

 

So true, so true. Lol~ :-)

 

Stock heads i think. This is a used built block that I purchased from a member on here several months ago (5000 miles on the rebuilt). He said it was running strong. I will redo the tests this weekend to ensure that I was at the end of the compression stroke, not on the exhaust stroke. But even TDC after the exhaust stroke, the intake valves should be closed, right?

Thanks so far. I'll post my exact test results this weekend.

 

just pull the valve covers already. look at the cam lobes to make sure if they are open or closed. its so much easier than trying to figure out your stroke and if you are exactly TDC.

 

just pull the intake manifold.....you can see right down the runners. watch the valve openings/closings. it is easy to figure out.

also, a tool like this one is great to have for finding TDC......


TDC Indicator for Deep Spark Plug Wells 10.75" Long

Accuracy is key for maximum cam and engine performance. Here are a couple ways to assure the number 1 piston is at true Top Dead Center. Installs as easily as a spark plug and is available in 6" standard length (46238) and 10.75" extended length (46237) with a 14mm threads. . Just remove the spark plug, screw in the gauge and rotate the engine observing the 1/8" graduation marks on the sliding shaft. Note the top of the piston stroke. Can be used with a dial indicator. Made in USA. Limited lifetime manufacturer's warranty