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Discussion Starter · #1 ·
I have been working on aHonda HT 3813 for a while now. I got it running when i first got, it had sit for years under an old satellite dish, but it would miss and had low power, starter was draging This year i was going to get it going good. I pulled the engine replaced the timing belt and found the water pumps teeth were worn out replaced that. Replaced the starter, put all new belts on deck. I thought i was good to go. Went to start it and it would not run. I checked the compression and had 35psi at each cylinder. Put oil in the cylinders retested compression and no change. I took the valve cover off to check the valves to make sure they were moving, but one thing i noticed while rotating the engine with the valve cover off it was squirting gas out of the oil drain hole under the valve cover. I had the gas turned off but i guess the bowl was still full. How could that even happen. So my knowledge of engines is above average and i know with compression that low valves are either not sealing or blown head gasket, even if rings were worn i should have more compression than that. But how is gas squirting out of the oil drain hole in the head.
 

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But how is gas squirting out of the oil drain hole in the head.
Hi gwbarm,

While I may not have the expertise to answer your question, there are some experienced Honda folks here that should be chiming in soon so check back!

One thing I would suggest in the meantime is confirming that the float in the carburetor is not stuck and letting fuel fill the crankcase and or cylinder.
 

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Discussion Starter · #6 ·
I did go back and check after thinking about it only oil should be shooting out of this hole and sure enough the oil is diluted with gas. So now back to my problem of getting my compression up. I am going to make sure the valves are adjusted right first and the only other think other than rings is the head gasket or a cracked block. Any thing i missed this is only the second one of these engines i have ever worked on the first one was a 4514 and it was overheating and shooting water out of the radiator. It ended up being a leaking head gasket. I have a lot of respect for these little engines and i will do whatever it takes to fix it, i am just trying the easy things first. Yes when it was running it was flooding it took a lot of effort to get it started blowing out black smoke i thought it was a timing issue because i had been through the carb 3 times , so that is why i replaced the timing belt. Its possible i have a bad carb also, but low compression is really concerning me.
 

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I really want to thank al that have replied to my post. I really appeciate the help.
I have a lot of respect for these little engines and i will do whatever it takes to fix it
No problem, we're glad to help! It's awesome you have that kind of mentality too about small engines. :cool

Good to hear you're another step further in the diagnosis process. It really sounds like the running issues are due to the carb. I would get the carb cleaned/rebuilt and see how it runs from there and then proceed to a valve adjustment and further look at the compression.
 

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Discussion Starter · #11 ·
I reset all the valve clearances, no change . I hope i will have a chance to pull the head this weekend, maybe i will find something there. I will keep you posted and anyone out there feel free to through out your ideas with this low compression issue.
 

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I reset all the valve clearances, no change . I hope i will have a chance to pull the head this weekend, maybe i will find something there. I will keep you posted and anyone out there feel free to through out your ideas with this low compression issue.
Thanks for the update.

Did rebuilding or cleaning the carburetor fix the running issue?
 

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Discussion Starter · #13 ·
I never rebuilt the carb i cleaned it 3 different times. Nothing changed. Still would not crank.

Maybe i should give a little more history on the mower. I bought it off craigs list. It had been stored under on old satellite dish for probably 10 years. I got it home cleaned the carb it wouldn't run, i pulled the timing cover the belt was 180 degrees off got that timed correctly and finally got it started it didn't start right away you had to wind on it for awhile and then it would start puffing like a train and start up, i suspect it had low compression then, i still think it was also flooding.. It never had much power and would only run for awhile before it would start sputtering. That is the last time it ran. I just assumed i must have missed the timing mark a little bit. I found a procedure on line to time the engine without using the timing marks he said it worked for him every time. Well it didn't work for me, and i new it wasn't right when i did it. The thing backfired and shot gas out of the carb at lightning speed strait at me. The timing belt was loose and i couldn't find the bolts to loosen the water pump to tighten the belt, so i decided to go at it full force. I replaced the timing belt water pump was a little stiff and the teeth were worn out so i replaced that and also the PTO clutch was not working so i replaced that along with all the deck belts. Reset valve clearances and still the same. So here i am all up to date i think my next attempt is to pull the head and see what i find there, but I'm afraid i may have to put in a new set of rings. Compression is supposed to be 170 and mine is 35.
 

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Discussion Starter · #15 ·
Yes it is about the same. 30-35 i put oil in the hole tried it again and no change. I am really hoping for a blown head gasket but i don't know enough of the history to know how its been treated.
 

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Discussion Starter · #16 ·
Update on the 3813. I tried using air pressure to determine where the compression was leaking i would pressure it up listen at the muffler nothing pressure it up again listen at the oil filler tube nothing, listen at carb nothing, took the valve cover off and i heard it coming up from the oil drain hole, so i concluded my test was bogus and inconclusive. Trying to think of what to do next, i knew the timing was right on because i had just put on a new timing belt and i had triple checked everything before i closed it up. I either need rings valves or a head gasket, so any of these three needs the head pulled, so that is what i did. It was not too bad i guess the hardest part was getting the timing gear off the camshaft but PB Blaster finally did the trick. Im not sure if the head gasket was leaking or not, but what i am sure of is it had been messed with at some point. It was completely stuck with some sort of gasket cement. I suspect that someone had a head gasket problem and fixed it without replacing the gasket , just used gasket cement. My plan now is to order a new head gasket, go ahead and check all the valves clean all carbon deposites, put on new valve guide seals and relap the valves. I will then put on the new head gasket hook the cam and timing belt back up and see if i have compression.
 

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my first guess is that if you have low compression you need rings and the cylinders honed. as for gas in the oil curious if it has a fuel pump? if so you may have a perforated diaphragm.
 

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Discussion Starter · #19 ·
Yes that is what i am thinking also. But being the same low compression in both cylinders so close to the same and so low makes me think maybe not.When you say honed do you mean rebored to the next oversize or just roughed up with the cylinder hone.
 

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Discussion Starter · #20 ·
You may be right i was hoping not, you can put lots of money into these engines in a hurry, i did mik the cylinders and they are in specs. I am just waiting for a head gasket, i checked out all the valves they were fine, it looks like they had been serviced recently. I went ahead and took each one out checked the guide and relapped each one. I will try the new head gasket and if that doesnt help all thats left is pistons and rings and a rebore. I don't like doing that this engine must have been really abused, probably run hot if it needs rings.
 
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