No compression

[bmstang]

I have a 235hp evinrude i did a compression test and the results were as follows. Cylinder 1 - 0 2- 105 3-0 4- 105 5-100 6- 105 i also did a wet test and the results on 1 & 3 did not change. I did see a little water in those cylinders but i was told even with a blown head gasket you would still get a little compression just wondering if the motor is shot or do i have any other options thanks

 

[Barnacle_Bill]

Re: No compression

Pull the head and see whats going on in there.

 

[emdsapmgr]

Re: No compression

You may just have a blown head gasket. That may be where the water is coming from. The compression on the other head is fine. Exhaust water leaks tend to affect the bottom cyls more.

 

[bmstang]

Re: No compression

I agree the head gasket is probably blown but i should still have some compression i do not have any and i did a wet test and still nothing I also understand when the top cylinders go out it is usually do to overheating. Explains why the person i bought it from put in a new water pump . A little to late i guess.

 

[emdsapmgr]

Re: No compression

If the overheat caused a ring to disintegrate, (certainly not uncommon on a crossflow) you may not get much of any reading on the compression gauge.

 

[bmstang]

Re: No compression

I agree that's why i am thinking it is more than the head gasket. I think if it was just the head gasket i would have got some kind of reading. I guess i am done cause the motor is a 78 and the boat is a 78 and i don't think i want to put that much money into it for a rebuild. I don't think it's worth it.

 

[Rscardina]

Re: No compression

in agreement,, head gasket.

cylinders 1,3,6 are on the same side. for 1 and 3 to have 0 tells me you blew it between the two.

pull the heads and see..but from what you desribe other than catastrophic failure, meaning cylnder walls blown through...then i am betting gaskets..

also if doing a comp test on 1 and 3..if they leak between each other you could get 0 becasue the flow is going into the other on the suction stroke..

 

[bmstang]

Re: No compression

Maybe i will try pulling a head off but i have never done it before. I can hold my own mechanically but i was told to be real careful cause the bolts could snap off.

 

[Rscardina]

Re: No compression

Maybe i will try pulling a head off but i have never done it before. I can hold my own mechanically but i was told to be real careful cause the bolts could snap off.

You will be fine..its no different and all we are talking is heads...be gentle on them , PB blaster if they looks corroded..just easy them out. you may snap one or two..but then again you might not..

think positive!! you may just find out you blew the gap between two cylinders.. an all you need is a gasket to trace down what may have caused it..

i figure an hour of your time..and worst case..you were thinking of junking it anyway..so whats to lose?

 

[bmstang]

Re: No compression

Thanks i appreciate it i don't know when i will get to it being that i have company in till next monday but when i do i will be sure to let you know what i found thanks

 

[emdsapmgr]

Re: No compression

When you pull the head, hope to see everything is OK and that the head gasket is the only problem. When you get the head off, check the head for small pits, dents. If a ring let go, the head will be full of them and may even have some ring pcs embedded in the head, piston tops. Also, check for aluminum scuffing (delamination) of the piston skirts to the cast iron cylinder liner. You can also pull the intake side (bypass) covers off those two bad cylinders to get a look at the piston sides and the rings. Just two cheap gaskets to put them back on again.

 

[bmstang]

Re: No compression

Thanks i will do that i appreciate all the info

 

[Tim Frank]

Re: No compression

I have a 235hp evinrude i did a compression test and the results were as follows. Cylinder 1 - 0 2- 105 3-0 4- 105 5-100 6- 105 i also did a wet test and the results on 1 & 3 did not change. I did see a little water in those cylinders but i was told even with a blown head gasket you would still get a little compression just wondering if the motor is shot or do i have any other options thanks

It wasn't me who told you that....
Seriously, a head gasket failure can absolutely result in zero compression.
Follow that trail first, as has been suggested by most.

 

[jz78817]

Re: No compression

I agree that's why i am thinking it is more than the head gasket. I think if it was just the head gasket i would have got some kind of reading. I guess i am done cause the motor is a 78 and the boat is a 78 and i don't think i want to put that much money into it for a rebuild. I don't think it's worth it.

like Rscardina said, no compression in two adjacent cylinders is very, very likely to be a blown head gasket.

besides, head gaskets on a two-stroke aren't usually that expensive, nor are they really that difficult to replace.

 

[bmstang]

Re: No compression

I agree i have nothing to lose i am going to pull the head & see what's up probably next weekend i will keep you guys posted thanks

 

[bmstang]

Re: No compression

Ok guys i got around to pulling the head and what i found was a blown head gasket. It was broke between cylinder 1 & 3 and around the 10 o clock position on cylinder 1. It was broke so bad that 2 pieces of the metal cylinder ring were missing around the gasket.The biggest piece being between cylinder 1 & 3. Cylinder 5 on the bottom i found a bunch of dents and pop marks on the piston and some on the back side of the head. I am guessing or should i say hoping it is from the piece of metal ring from the head gasket. That is odd because that cylinder had compression of 100. I hope a ring did not let go on that cylinder. All of the cylinder walls looked perfect no scratches or anything real smooth. I did find only 1 water diverter between the cylinder sleeves i was told there should be 4. I have them on order.

 

[Rscardina]

Re: No compression

there you have it! I'll say it.....WE TOLD YOU SO..NA NA NA

But seriously, the gasket blowing happens..did the pieces create that wear??who knows. The fact that the cylinder walls look good tells me things seem to be ok thus far.. the marks could have been there before you got the engine,,wrong length plugs can make those marks..
change the gasket, put the diverters in..and bolt her down..run it and get back to the water...

 

[bmstang]

Re: No compression

I put the diverters in there seems to be two spots in the middle for them but the other two don't fit anywhere but on the ends so i put them there besides there was one on the end pushed way down don't know if that is the wright location or not. started to bolt her up and ran into a problem is this ever gonna end seems somebody at sometime put a heli coil in third bolt down inner between cylinder 3 & 5bolt on outter part of the head. The bolt will not tighten down and stripped the lower threads on the only bolt that was different from the rest it had to have a washer added to it. I tried one of the other bolts it didn't strip but will not lock down just keeps turning does one matter or what should i do i am off to lowe's now.

 

[bmstang]

Re: No compression

i GOT THE HEAD TORQUED DOWN NEEDED 3 HELI COILS AS THE BOLTS WERE JUST EATING THE THREADS AWAY. I can't torq to spec as they just keep turning but i got them tight enough i believe with the regular ratchet. I did another compression test and the results were #1-95 #3 105 #5-105 #2-110 #4 110 #6-110 just getting ready to fire it up & take it out.

 

[gspointer]

Re: No compression

I am afraid you will probably have issues. I would make sure the diverters are in the right place. (I assume you are talking about the rubber hoses that go between the cylinder and water jacket) I believe these in the wrong place can destroy your block. I suspect you will have issues with your heads also. I might be willing to run with the heads not torqued right. (I would not be suprised if I didn't get much life out of them) Unfortunately I suspect your block needs a visit to a good machine shop to repair the bolt holes for your heads.