Honda D Series Forum banner

1 - 17 of 17 Posts

·
D-series wise guy
Joined
·
2,858 Posts
Discussion Starter #1 (Edited)
I originally posted this here : http://www.superhonda.com/forum/showthread.php?t=257985

This is a general howto on performing a leakdown test. A leakdown test basically tells you how well sealed your combustion chamber is and give you more information about the general health of your engine than a compression check will. A leakdown test will help you pinpoint if you have a bent valve, bad ring seal, bad valve adjustment, scratched/scored cylinder wall, etc.

Time involved : ~1hr

Tools Required :
- leakdown tester
- air compressor
- 10mm socket
- spark plug socket
- 18mm socket
- 12" extension
- ratchet
- floor jack

The first thing that you need to do is make sure that the car is properly warmed up. It is best do go for a little trip around the freeway, and come back home


1 - You can see in this first pic that I have already pulled all of the spark plug wires and removed the spark plugs. You can also see that I have the distributor disconnected. No need to do that. This picture is actually from when I did my compression check. You will notice that the cam gear cover is still on.



2 - The next step is to remove the cam gear cover. If you have not already modified your cam gear cover, then you have to remove the entire valve cover to gain access to the cam gear. If you have to remove the valve cover, then it would be a good time to replace the valve cover gasket and you will need some hondabond/sealant to reseal the gasket when you re-install.



3 - Jack the car up and remove the driver's side front wheel. This will give you access to the crank pulley bolt. You can see that I've already got the 18mm socket, extension and ratchet in place. You have to turn this counter-clockwise in order to turn the cam gear.



4 - Here is a picture of the leakdown tester. You will notice 2 gauges. The gauge on the left tells you how much pressure is coming from the air compressor, and the gauge on the right tells you how much is coming from the engine/cylinder. The big yellow knob is a regulator so that you can control how much air is coming from the compressor. My compressor also has a built in regulator.
 

·
D-series wise guy
Joined
·
2,858 Posts
Discussion Starter #2
5 - This is an air compressor :) The compressor needs to be able to put out at least 125psi.



6 - Notice here that the leakdown tester hose is screwed into cylinder #1. The spark plugs have already been removed.



7 - Here, we set cylinder #1 to TDC by turning the crank with our trusty ratchet. It is hard to see in the pic, but you can see the "UP" at 12 o'clock on our cam gear.



8 - This pic got a little hard to see once I shrank it down. These are the gauges on the air compressor. The guage on the left is how much pressure is in the tank, and the guage on the right is set to 120psi. We need to be able to blow enough air into the leakdown tester.



9 - Now we connect the blue hose in the cylinder #1 to the leakdown tester. The leakdown tester has the knob on the left guage set at 100psi so we are blowing 100psi of air into the cylinder and we can see on the gauge on the right that we are reading 98psi from the cylinder. 98psi/100psi = 98% which means that we got back 98% of the air we put in. So that is 2% leakdown for the cylinder. That is pretty impressive for an engine with > 120k on it :)

Now that we know how to do the check, rotate the crank 180deg (which is 90deg on the cam gear), so that the "UP" is at the 9o'clock position for cylinder #3, move the tester to cylinder #3, and repeat the test. Then rotate again, so "UP" is at 6o'clock for cylinder #4, repeat test. Then rotate again so "UP" is at 3o'clock for clinder #2, and repeat test. You go 1-3-4-2 because that is the engine's firing order.



This is not a step, but it shows my cam gear cover modification. You can see around the top where I removed the lip with a dremel. This lip fits under the valvecover and is why you normally have to remove the valve cover to remove the cam gear cover to get to the cam gear. If you cut this lip off, then you can get to the cam gear without removing the valve cover and you still get to use the cam gear cover to prevent dirt/debris from getting down in there.
 

·
the MAD scientist
Joined
·
2,574 Posts
If a cylinder is leaking try to find where the air is coming out.

If its coming out the exhaust, you have a bad exhaust valve
Coming out of the intake, bad intake valve.
Coming out of the valve cover, bad rings.

What did I forget?
 
W

·
Guest
Joined
·
0 Posts
If it is leaking from the bottom end, then the rings are shot. If you open the throttle plate and hear air escaping, then the valves are bent. Otherwise, if you remove the radiator cap and air bubbles appear in the coolant, then your headgasket is blown.


this is from c-speed
 

·
the MAD scientist
Joined
·
2,574 Posts
Oh yeah, forgot the head gasket.

Where do you listen for the air coming out of the bottom end?
I guess from the PCV..
 

·
Registered
Joined
·
4,363 Posts
1 - 17 of 17 Posts
Top