Compression Test to Check Generator Engine Valves

[@williegillie5712]

Valve adjustment is very important. As the valve wears the clearance changes. This causes harder cranking and in some cases can cause premature wear of the starter and valves. Thankfully some engines have hydraulic lifters and need no adjustment. I had a Kohler with hydraulic lifters on a riding mower. It was nice not having to adjust the valves every 200 hrs with that engine. The only problem I had with the hydraulic lifter Kohler Command 15 ohv was the compression relief quit working and I had to replace the spring that broke on that. When the compression release quit working it burned out a starter so It had to be fixed. The hydraulic lifter small engines were my favorites. Good to see ya using distilled water to fill the battery.

[@thehvachacker]

I like the Kohler command engine it’s what’s in the Kohler Generators I work on. Yes he hydronic valves are nice. I have had a spring break on the Kohler engine also. Yet checking valve lashing on all engines that need it is important. Also checking it correctly too dead center. I had a coworker who was checking top dead center wrong and over tighten a few valves.

[@TheAirboss1955]

Good video, great information. Keep up the good work

[@GrumpyUnkMillions]

Doing a compression test will reveal bad valves. It will NOT check the valve lash or clearance. As the parts wear in an OHV engine, the clearance will open up generally. If the clearance gets to be too large, most compression releases built into many engines will not work properly. When the compression release no longer functions, the starter motor has to work harder to overcome the pressure, and may not be able to overcome the compression. To do the recommended valve adjustment is not just to test for bad valves and low compression. Generac may do things differently, but the valve lash should at lest be checked on a regular basis after so many hours of operation.

[@michaellicitra7632]

Yes you are correct. In fact, the valve clearances must be checked and reset if necessary. Valve clearances differ from cold to hot engine temps. Remember this is a safety device and while it may look ok, compression tests do not indicate proper valve adjustment. The engine could fail if when reaching operating temp the valve clearances went out of the acceptable range.

[@johnbarton1878]

Best video I've seen on how to check and service a generac yet, good job.😂

[@ggibson511960]

You took great pains for nothing to open the throttle to get an accurate compression test reading. Notice how the pressure jumps up incrementally on each intake stroke. The cylinder pumps itself up until it can draw no more from the intake manifold. The compression test readings will be accurate as long as the engine is allowed to pump up the cylinder until it can’t pump any more. A little valve clearance understanding is in order. Valve train lash is necessary to allow valves to seat and be cooled. These light duty air cooled engines run hot, especially the heads. Exhaust valves are the first to go. New engines seat their poppet valves deeper in the seats as they run in, decreasing the lash clearance. That’s why Generac wants you to check valve lash at 25 hours, the let it run till 400 hours. Excessive valve lash will hammer the tappet and cam profile surfaces. Clearances are determined by the manufacturer with careful run testing to ensure a tiny bit of lash remains when the cylinder, heads and valve train warm up.

[@wysetech2000]

If the compression is low it could mean the valves are already leaking and possibly damaged from being too tight.

[@bigskynetworks4213]

Hi, thank you for the video. How much would you charge for a maintenance service: change the oil, both filters, value/compression adjustment/check? Thank you : )

[@throttlebottle5906]

going by the oil look while draining, the poor thing still had the original break in oil :|

[@thehvachacker]

I wouldn't be surprised if this is the first time this machine was servicedt

[@tallbrian100]

Gererac oil and filter, is the unit still under warranty?

[@thehvachacker]

It is include with their contract the spark plugs, air filter and oil change. What’s wrong with generac OEM parts?Plus we perform many other tests and service. Next year I will actually check the valves and brushes. Then the year after just the combustion test

[@alfoncejean8826]

@@thehvachacker an emergency generator where you need to get a third party to do your mantenance... am I the only one seeing the HUGE problem with this?

[@jonnymac31]

@@alfoncejean8826 yeah pretty much.

[@jeffcoolhd]

Hacker the video was very educational thank you. Peace brother

[@gairyjackson9366]

good day just did compression test on my genrac and get chamber one 135 and chamber two is 155

[@THEtechknight]

Damn. never got to hear it run :-(

[@thehvachacker]

Sorry, I should have started it for the video.

[@pineychristian]

Great video HVAC Hacker. So I have some questions. So you have a 20kw generator and i saw 5 AC condensers. They all for same home right there? Also what can a 20kw generally do?

[@thehvachacker]

Yes those are for one home. The generator can handle about 80amps of power. I think Mabel 125amps for split second LRA. Yet you never want a generator running at 100% load. They were designed for emergency's yet people want there house to operate as if they never lost power. You can get 1 ac matey 2 if not many loads in the house is on

[@pineychristian]

@@thehvachacker thanks for info. I have 2 AC systems. 2 tons each. So it would be nice to size generator to be able to run majority of house. The Generac generator looks tech friendly.

[@alfoncejean8826]

@@pineychristian WHAT those things ?? thech frendly in what univer? you cant posibely be serious.

[@pineychristian]

@@alfoncejean8826 can't be that bad. I worked as a Auto tech for 16 years before going to HVAC trade. Let me tell you some of the jobs working on cars and trucks total nightmares. We had to use are Braille skills. Some cars I will not touch ever again.

[@gerryvanwoerkom7241]

did you figure out why there was oil in the air filter compartment

[@thehvachacker]

The causes of oil in the air filter box is a prolonged operation of engine or oil could have been overfilled at some point.

[@skevies.9564]

Hello what kind of ratchet wrench were u using to take off both of the spark plugs. What is it called? Thanks in advance!

[@ItsMe-dj8zd]

The time it took you to check the compression you could of just pulled the covers and muffler cover panel and checked the valve clearances. 5-7 minutes start to finish. Low mark to full mark is 4-6 ounces, your oil level would of been fine for a compression test.

[@thehvachacker]

We all have different ways of achieving the same outcome. I compression one yet. Next year will check actual valve clearance. As for the oil I had to do an oil change anyway so decided that was a good time.

[@joeshearer1247]

The air filter seemed like it was upside down. Guess they engineer it that way

[@davidhobson8284]

We do both every year compression test and valve clearance adjustment on our 22 KW Evolution. It just takes a few extra minutes once a year. Also the oil in the air filter box could be caused by the low oil condition (oil getting hot/vaporizing too much) or extra cold conditions such as Josh referred to on GP Outdoors video. If the situation is due to cold conditions Generac now has the extra heating add on system www.norwall.com/products/Generac-Breather-Heater-Kit-for-Air-Cooled-9-22kW-7103/ Still waiting to see what GP Outdoors does with his on this. Also the oil needs to be changed HOT instead of cold to get all of the contaminated oil out at drain. Also ( and this is just personal preference ) never lube the new oil filter gasket with old oil, if you have fuel contamination it will affect the new gasket on the filter (US Navy training). Always use new oil on a NEW Oil filter. Also remember that the Generac system run/test time every week DOES not exercise the entire system ONLY the engine. To exercise the entire system ( Engine/Generator/Transfer switch ) outside utility power must be turned off which will make the entire system work/exercise INCLUDING the transfer switch (if it doesn't switch over = no power to the house) which means the neighbors are laughing at you cause your sitting in the dark now too! And finally Hacker this is NOT a slap at you but sometimes homeowner education is needed (ie checking oil every 7-14 days, running unit under load as appropriate ect) in the long run you will have a happier customer because you are telling them the way it is instead of selling them sunshine and happy days and they will appreciate you for doing so ( well maybe not that day but common sense will kick in eventually LOL) Just remind them they have a BIG money investment in this unit and the little bit of time they spend on this WILL payoff big time when the power does go out.