Removed Head to Investigate. Here's what I found.....

[redfarmer84]

So here is the next chapter in the process of evaluating my 1976 Briggs 5 hp engine.

Since I was getting a 0 psi compression reading (I got 30 psi the day before), I thought that I had to remove the head to evaluate further. I found the head bolts to be just snug....not real tight at all. I also noticed that the head was just floating on the block without being "stuck" like I figured it would be. The head gasket looked new and clean, the piston and valves were good looking with the exception of being really wet and having some "sludge" on them. The inside of the head also had a bunch of sludge on it.

I used some brake parts cleaner to spray everything down well and wiped it all out. I even used a small pick to scrape some of it off. None of the stuff was hard, as it was all wet and like a sludge rather than hard dry carbon. All of the valves moved up and down and the piston wall was smooth.

I cleaned it all up well and did the valve test where you put the engine at TDC and push the valve down and try to spin it. Neither of them moved at all, so seemed to be seated tightly.

I decided to put everything back together and snugged all bolts then went back and tightened them in a star pattern a little bit tighter (didn't use a torque wrench since I am still diagnosing) .

Now, I need some input from the pros on what I have found and what is possibly wrong, then what I need to do next.

 

[redfarmer84]

sorry for multiple posts to post the pics. the ipad only allows me to do it tht way that i can find

 

[redfarmer84]

pic 3

 

[redfarmer84]

pic 4

 

[redfarmer84]

pic 5

 

[WrenchDad]

What are you using for fuel Pudding? That is really wet. Seeing as it is really wet on top of the piston and on the head in the combustion chamber I would say your getting oil coming past the rings. That may also explain 0 psi, Now I cant tell you what caused it but it doesn't sound like a valve is sticking.(at least not the way you checked it).But I suppose you could have broken a valve spring and the exhaust valve is staying open.:shrug:

 

[Stangrcr1]

Sounds like the head bolts were loose enough to allow the head to warp. This allowed all the compression around the head gasket. Most common area is around the exhaust valve.

Check for spark, and if good, try to fire it up...

 

[Docdc]

If you have a compression tester, check the compression. If it's at zero, pull the piston and make sure a ring isn't stuck. If that's all good and you have spark it should at least hit with a little ether.

Doc

 

[125ccCrazy]

the carbon on the head is pretty common for these engine with years of use,, all the fuel on the piston could be explained by the head leaking and not burning off.. I'd change the oil and give it a shot... sounds like it may just be improper maintenance and repair from the prior owner..

 

[Txpowdercoater]

bolt it up tight and fire it up

 

[redfarmer84]

hey guys....like I said and showed in the pictures, I cleaned everything up and bolted it back up and tried to fire it.

(edit: there was no "hard carbon" anywhere. Everything was wet on engine and head and simply wiped clean)

It would not necesarilly "hit", but had a little bit of a sputter as where it didn't before. Pulled it about 5-6 times and tried just a taste of ether. Nothing. Tried the compression test and it read about 15 psi. Both valves were moving up and down properly and not sticking. This engine was mounted on the old mini bike which was found in an open-air shed/barn. The owner just had passed and was 93, so who knows how long it had been sitting there?? He was an engineer and had built many things like an airplane and VW kit car (which I got), so you'd think he would have given it the best of maintenance.

 

[KustomKartKid]

I think I mentioned this in one of your other threads but did you look to see if it has a compression release. I'm not real familiar with them, but even the older Briggs 5's from the 60's have the "Easy Start" decal on the recoil. This leads me to believe they had some kind of extra bump on the exhaust lobe or a centrifugal dog that acts as a compression release. Motors like this typically have low compression numbers when turning it over by hand and if the release is somehow sticking it won't run at all.

 

[chatten63]

I have noticed ,that give the motor about 3 good pulls and you should have a good reading on your compression gauge,this is for the compression release motors.found 10hp have around 60 on gauge and 5hp around 35-40 on gauge:shrug:

 

[Miniwood]

You need to check your valve gap! Whit the piston at TDC ( which is actually down about 1/ 2 inch from the top ) can you push down on the top of each valve an spin it in circle you should feel resistance ,,,,, if it spins too easily then its not shuttuing all the way.
If the valves are shutting tight then you neeed to check your piston rings !

 

[redfarmer84]

I have noticed ,that give the motor about 3 good pulls and you should have a good reading on your compression gauge,this is for the compression release motors.found 10hp have around 60 on gauge and 5hp around 35-40 on gauge:shrug:

I bet for some reason it is sticking then! When I get home tonight I will torque the head to 12 ft. lbs and look at the compression release to see if it is sticking. Yeah, I got around 30 psi the first time I had checked it with about 3 pulls. Then the subsequent times, I only got 0 psi or 15 psi at the max. with multiple pulls.

The question is: how do I check the compression release?? Where do I even find it? Should I just search this forum for the topic when I get home tonight?

 

[Docdc]

Pull it three times and get a compression reading. Shoot some oil into the spark plug hole, put the plug back and pull it three times again. If you get lots more compression the second time, you have a ring problem or problem with the cylinder sealing. (out of round, worn out of specs or scored.)

Doc

 

[Miniwood]

Bet its the exhaust valve nit closing right!