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I have a 4yr old INTEK that is slowing loosing power. (Engine Model #33R877/0008-G1)
New camshaft - 10/27/23 which fixed the broken compression relief. Seemed to run great after I put it back together.
After mowing six times this year I have low power and it is getting worse.

What I have done so far that has not helped at all:
Tune up 6/01/24 - Air filter, fuel filter, spark plug
Checked flywheel KEY - it was fine
Checked valve adjustment - it was fine
6/7/24 - Replaced carburetor and it runs slightly worse...won't idle all the way down
Always kept good clean oil in it. Because it lugs down more when mowing I removed the deck belt and spun all the spindles and pulleys which were fine.
Questions:
Could the compression relief be stuck giving me low compression (hard to check and never heard of that happening)
I see some INTEK engines have head gasket problems - I see no sign of that, no oil leaks, smoke, or odd sounds.
I have mowed 1/2 acre of level lawn six times and it seems like I have about half the HP I should have.
Thanks for any ideas or things to check.

Could your drive belt be slipping? It would be helpful if you posted the model number and name of your mower!

When these Intek blows you usually will not see smoke or oil leaks as they blow between the cylinder and push rod galley which produce excessive crankcase pressure which vent via PCV system into the filter side of the carburetor. One sign of this is excessive oil usage. Modern oil just don't smoke like older oils so a lot of the time you will not see smoke.

Mower is a Troy Bilt Bronco 42" Model# - 13AL78BS023

I will check for pressure from the PVC hose. Thanks.

If checking the hose you are looking excessive amount present.

But is better to do a leak down test with the rocker cover off. This way if the head gasket is blown between cylinder and the push galley you will hear a louder air sound escape there than at the oil fill tube. Now the sound is louder at oil fill tube then its the rings and cylinder leaking. IE worn out.

While you're doing the leak down test, I'd also do a compression test.

GearHead36 said:

While you're doing the leak down test, I'd also do a compression test.

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I know a compression test would tell the condition of the head gasket however I assumed the compression release on the cam would prevent getting a good reading.

Just ordered a Leak down tester on Amazon. I will have it late next week and will let you know what I find.

Just did a leak down test and there were NO noticeable leaks! I did notice the exhaust valve gap was a little loose. Decided to roll over the engine and check both gaps. To my surprise the exhaust valve had about 1/4" travel HOWEVER the intake valve had almost NO travel. I tried to measure with a ruler and it looked like 1/16" travel at most. I guess it's time to split the case and look at that after market cam I put in late last summer. Seems really odd to have trouble with a lobe??

Have come across a few OEM Briggs that delobed the cam

After looking at some bad camshaft reviews on Amazon, it seems several people had worn lobes after anywhere from 20 hours to a couple years. I just ordered the OEM camshaft. I don't go cheap on replacement car parts, guess the lawn mower is no different...live and learn.

MRay70 said:

After looking at some bad camshaft reviews on Amazon, it seems several people had worn lobes after anywhere from 20 hours to a couple years. I just ordered the OEM camshaft. I don't go cheap on replacement car parts, guess the lawn mower is no different...live and learn.

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Good luck!

What is the symptom indicating low power? Speed decreasing? Blades turning slowly? If speed is the indicator, the trans itself could be the problem, especially if it's a hydro.

Had one in the shop several years ago that had worn the intake lobe almost round so the valve was only open for a short period of time. Symptoms were the throttle butterfly was being pulled to the full open position by the governor spring but the engine would only run 2400 rpm.

Before reading of the altered valve lift, I was going to suggest checking the governor linkage to see that it was attempting to provide full throttle when the load increased. I would also compare valve stem height on both valves and the rocker arm mount to be sure it had not started to move out of the cylinder head.
tom

I will check valve/rockers when I put it back together.

Got the OEM camshaft. Looks like an upgrade and came with new tappets. Too bad the crankcase gasket has been delayed a few days. Guess I will just hang out watching the grass grow.

Back together and running at full power. Mowed pretty high grass with ease. After market cam intake lobe was worn off to almost round. Found some silver sludge in the bottom of the crankcase from the lobe. Fresh oil and filter and all seems well. I did put the OEM carb back on.

Thanks for letting us know you have found the issue and now have it repaired.

MRay70 said:

Back together and running at full power. Mowed pretty high grass with ease. After market cam intake lobe was worn off to almost round. Found some silver sludge in the bottom of the crankcase from the lobe. Fresh oil and filter and all seems well. I did put the OEM carb back on.

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Thanks for the update.

MRay70 said:

After looking at some bad camshaft reviews on Amazon, it seems several people had worn lobes after anywhere from 20 hours to a couple years. I just ordered the OEM camshaft. I don't go cheap on replacement car parts, guess the lawn mower is no different...live and learn.

Click to expand...

So you are telling me an aftermarket camshaft had worn lobe after 20 hours of use? I find that difficult to believe, at best. I have put in more than one aftermarket camshaft when the compression release mechanism breaks, and have never had a comeback.

Tiger Small Engine said:

So you are telling me an aftermarket camshaft had worn lobe after 20 hours of use? I find that difficult to believe, at best. I have put in more than one aftermarket camshaft when the compression release mechanism breaks, and have never had a comeback.

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I didn't either.... Until I did!
I had an aftermarket fall in 17 hrs.
No lobes were worn but they were slipping and spinning on the splines that are supposed to hold them in place.
Lousy quality metal and likely assembly too.
I used a number of aftermarket with no issues but that was several years ago.
This one that failed was purchased May 2021 and failed Sept 18 2021.

I didn't have any issues with previous ones.
I replaced that one (again) with a Briggs with a newer longer part number and this is it's 3rd season on that Briggs replacement camshaft.

Maybe by now they have improved the aftermarket ones or maybe some are better than others although most all I have seen look identical like they were all made in same factory but who knows...
I have no faith in any of their quality and I don't have much more faith in the Briggs part as the original ones fail FAR too many times and they haven't improved the design one noticeable bit.

MRay70 said:

Back together and running at full power. Mowed pretty high grass with ease. After market cam intake lobe was worn off to almost round. Found some silver sludge in the bottom of the crankcase from the lobe. Fresh oil and filter and all seems well. I did put the OEM carb back on.

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After Market Cams are not worth the time or the money. I had to redo five customers engines that had after market cams installed at a different shop. All five runs great now oem cams.

jayswailes said:

After Market Cams are not worth the time or the money. I had to redo five customers engines that had after market cams installed at a different shop. All five runs great now oem cams.

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I have used aftermarket camshafts and no problems. Remember, many of these OEM parts are made in China also, just to different specs and tolerances.

Tiger Small Engine said:

So you are telling me an aftermarket camshaft had worn lobe after 20 hours of use? I find that difficult to believe, at best. I have put in more than one aftermarket camshaft when the compression release mechanism breaks, and have never had a comeback.

Click to expand...

Very different experience here as I installed three after market camshaft and all three failed withing six months. This back when Briggs cams was so hard to come by then I found the two software misplaced OEM cams. So I haven't even tried any further after market camshafts. On my fourth camshaft replacement this year, all have been replaced the newer OEM camshaft.

TobyU said:

I didn't either.... Until I did!
I had an aftermarket fall in 17 hrs.
No lobes were worn but they were slipping and spinning on the splines that are supposed to hold them in place.
Lousy quality metal and likely assembly too.
I used a number of aftermarket with no issues but that was several years ago.
This one that failed was purchased May 2021 and failed Sept 18 2021.

I didn't have any issues with previous ones.
I replaced that one (again) with a Briggs with a newer longer part number and this is it's 3rd season on that Briggs replacement camshaft.

Maybe by now they have improved the aftermarket ones or maybe some are better than others although most all I have seen look identical like they were all made in same factory but who knows...
I have no faith in any of their quality and I don't have much more faith in the Briggs part as the original ones fail FAR too many times and they haven't improved the design one noticeable bit.

Click to expand...

It depends where you buy them from
Never ever had anything fail that was bought from Alibaba ( not ali-express ) or Made in China .
OTOH have had so many failures with stuff bought on Amazon or Ebay that I stopped buying stuff from there near a decade ago .