How Much Compression Should your Golf Cart Have?
You can get a good feel about your engine’s condition by checking its compression. The vast majority of gas engines should have a compression of about 150 psi.
If your golf engine is new then your compression should be between 150psi – 160psi. A used engine that’s still in decent enough shape should be at around 120psi to 140psi. Anything below that might run alright for a bit longer but it’s probably time for a rebuild if your engine has compression that low.
How to Do a Compression Test on your Golf Cart
If your golf cart has been losing power or has been running less than smoothly, it might be because of a lack of pressure in its engine’s cylinders. If that’s the case, it’s probably time to do a compression test on your golf cart.
If there’s a drop in compression in your engine, it’s probably because air is leaking out from some point in the engine.
If your engine has a problem with hard starting, has erratic idling, has a loss of power when carrying heavy loads or is difficult to start when the engine is hot, you probably have low compression.
To check if pressure is escaping your golf cart’s engine, you have to check the compression in the cylinders of your engine using a compression gauge.
A compression gauge measures the amount of pressure your golf cart pistons exert on the fuel and air mixture before the mixture is fired up by the spark plug.
How to perform a compression test on a golf cart:
- If your engine has a cylinder cover, unscrew it and then take it off using a screwdriver. This is so that you can access your engine’s spark plug.
- Use a flat headed screwdriver and get it under the edge of the rubber boot. Without using too much force, remove the rubber boot from the spark plug.
- Put a socket wrench over the spark plug and loosen it till you can remove it from your cart engine.
- Put the choke in the off position. The off position is also known as the closed position.
- Purge any leftover fuel left in the cylinder or crankcase by cranking the starter cord of your engine a few times.
- Put the hose of your compression gauge in the spark plug hole.
- Pull your engine starter cord 10 to 20 times or just till the compression gauge’s needle reaches its maximum level.
- Check if your car engine’s compression is high enough or too low.
Compression gauges are affordable and easy to use. Some need to be held in place to take the measurement while others need to be screwed in the spark plug opening.
The best method to use for a compression test is the aircraft mechanics test which is also called the “leak down test”. You do this by applying air pressure into your engine’s cylinder with the piston being held at TDC compression stroke. This test lets you know where the air leak is and where the loss is coming from.
Low compression VS High compression
First things first, you should know exactly what compression means in this context.
Compression ratio is the ratio you get when you compress the max cylinder volume of your cart engine into the min cylinder volume of your cart engine. This is the volume of your engine’s cylinder when one of its pistons goes all the way down compared to when one of its pistons is all the way at the top. As an example, you’d say an engine has a 8:1 (said as 8 to 1) compression ratio.
Your carts engine power is generated when force that’s created by the combustion in your engine is exerted on the engine pistons. The pistons are pushed down the cylinders. The higher the pistons are up before the combustion starts, the higher the force that’ll be exerted.
As the compression ratio goes higher, the pistons also move higher and there is more force for what’s known as the expansion stroke. More force for the exact same amount of fuel means better efficiency.
The important thing you need to get from this is that a higher compression ratio means your engine is more efficient. From the same amount of fuel, you get more work from your engine which is good for power as well as miles per gallon. Higher compression is better for your efficiency than low compression.
Higher compression means more thermal efficiency. If your engine has a low compression ratio, you may run into the problem of excess waste heat being produced that isn’t being used for mechanical work.
A higher compression ratio means better thermal efficiency which means more horsepower, higher fuel economy and better performance.
If all these advantages are true, why do people use lower compression engines? Cost; high compression engines need premium, high-octane gasoline to run properly. Also, they’re made of higher quality metals to withstand the stress of being high compression so the engines are expensive.
Higher compression also means more pressure. That means there’s more mechanical work for your engine and will this extra work wear your engine down faster.
How to Fix a Golf Cart with Low Compression
If your golf cart has low compression, it’s probably because of an air leak somewhere in the engine. Fix the air leak and your engine is back to normal.
- A bent valve.
Take a look at your carts engine and check your valve clearance. If your valves are bent then your engine should be able to start but it will idle badly and won’t be smooth. There should also be some power loss.
If this is the problem, a professional mechanic might be able to fix your bent valve if you’re lucky but more than likely you’ll need to replace it with new parts.
- A burnt piston.
Look in your carts engine and check for holes. If your pistons are burnt, they’ll look melted or have holes burned right through the top of the piston. This is usually because of too much heat in the combustion chamber.
If you have a burnt piston, it’ll cause low compression in your engine because your burnt piston can’t work properly. You can’t fix this and need to replace the pistons with new ones.
- A blown head gasket.
Simple enough, you’ve got a broken gasket in your engine that’s not sealing properly which causes air leaks and low compression.
Check and see if the gaskets in your engine are still in good shape. If they aren’t, they need to be replaced right away.
- Stuck rings.
If your rings are stuck, your engine won’t run properly or at all because of low compression.
To fix this, pour in 1 to 2cc of ATF into your engine’s spark plug hole. Then recheck it. If it gets higher, you need to pour more ATF in and then let sit for a day.
Afterwards, change your oil.
- A loose spark plug.
Your spark plug needs to be torqued just right; not too tight, not too loose. If it’s not, then your spark plug may overheat and cause a misfire.
This is a simple fix. If your spark plug is just loose but still good then you only need to put it back in place. If your spark plug is busted though, you’ll need to replace it.
- A clogged exhaust.
If your cart engine can’t pull in fresh air, then it’ll have low compression. So if your exhaust is clogged, your cart engine gets low compression.
To fix this, just clean out your cart’s exhaust and make sure your exhaust is functioning properly in general.
- A bad gauge.
This is the happiest mistake you can make. Maybe you don’t have low compression and it’s just the gauge you’re using is getting the wrong reading. Go ahead and replace your old gauge.
How to Fix a Yamaha (G2) golf cart with no compression
Yamaha golf cart engines in general have a pretty common problem that causes low or no compression; misplaced push rods. A push rod that’s not under the rocker arm will cause a compression problem. This is easy to check and relatively simple to fix.
To check this, take off your engine’s valve cover and see if one or more of the pushrods came loose from the rocker arms.
If your pushrod is loose, this indicates possible excessive clearance for the valves. This means that the top parts of your engine are not getting enough oil. Simply tightening the valves should fix your compression issue.
If there’s not enough oil getting to the top parts of your cart engine, there’s a way to fix it.
- Remove the steel tube that goes through the back of the motor.
- Blow through it.
- Take a wire and push it through it.
- Take off the oil fill cap.
- Put a rag over the oil fill tube to prevent oil from splashing on you.
- Blow through it again.
- Replace any short oil hoses with longer fuel injection hoses.
- Change the oil before you run your engine again.
This should fix your oil problem and fix your low compression.
How to Fix a Yamaha (G9) golf cart with no compression
Yamaha G9 engines also have the push rod problem. They might become misaligned or out of place and need to be fixed just the same as the G2 engine.
Another thing that might have happened to your G9 is that the push rod isn’t just out of place, it might be completely bent. The rocket support arm in your engine may also be completely broken. If this is the case, you can’t fix these parts anymore and must replace them with new, functional parts.
After you do that, your engine should work properly with no issues with compression.
How to Fix a Yamaha (G16) golf cart with no compression
If your Yamaha G16 has no compression, check that it doesn’t have any of the problems listed in the Yamaha engines above. Again, all Yamaha engines tend to get their push rods out of place after some time.
If the push rods, rocker support arms and oil aren’t the problem, it might be your accelerator cable. If your G16 has a broken accelerator cable then it won’t be able to run because there’s no compression. If your accelerator cable is broken, then you can’t fix it and must replace it.
Replacing the accelerator cable should fix the compression issues in your G16.
How to Fix a EZGO golf cart with no compression
A common problem with EZGO golf carts is the valves getting messed up. If your cart engine has no compression, start by checking the valve lash. Usually a valve adjustment will fix your compression problem right away.
If it’s not the valves that are the problem then the next thing you want to check is the cam timing. It’s an uncommon problem with EZGO engines, but the timing belt may have jumped or one of the gears or pulleys may have come out of place.
See if you can fix the timing belt or gears or if they’re just misaligned. If any of the components are broken, you need to go get new parts and replace them. Doing this should fix your compression issues in your EZGO engine.
Lastly, you should also check the push rods and rocker arm supports of your EZGO engine. While this problem isn’t relatively uncommon on EZGO engines, it’s still a possibility. Fix any misaligned pusher rods and replace any broken parts.