Logo
FULL SITE MENU

Help New boatie

A

arzy

Member
Hello all, I have just joined your forum. I have purchased a Haines Signature 1550C with a 90HP Evinrude (E90TXARC)

My question is that it appears to have low compression, I just checked it cold from a compression test borrowed from work (Toyota).

The readings were taking on a cold engine and not with the throttle opened, so I may have to re do this.

I got 100 Psi on three cylinders and 75 on the other, this I am guessing is not good? once started the engine runs faultlessly.

Any advise you have would be appreciated, I would like to get some use before I have to go through an engine rebuild or rings replacement.

Thanks again
 
Advice on compression testing HERE

But if it runs "faultlessly" ...................

If you still get one low reading after re testing as above maybe the next thing to consider is a Seafoam decarb.

.
 
Last edited:
I have used a can of Evinrude engine tune, will run tonight and report compressions readings. Any chance of a link to a service manual?
 
Compressions results are in

Ok warmed engine up this time

cylinder RHS top 75PSI, with oil added 75PSI
cylinder RHS bottom, 100 PSI, with oil added 105PSI
cylinder LHS top 100 PSI, with oil added 115 PSI
cylinder LHS bottom 115 PSI, with oil added 115 PSI

Looking at the head I am suspecting the gasket for leakage, as the compression should have raised with the oil added if it was in the rings, am I correct in this assumption. Any write ups on replacing a head gasket? the one I am going to replace look seperated at the top and rusted.

Any help appreciated
 
Surely with oil added the Compression should have increased if the cylinder was scored, due to the fact the compression stayed at 75, it must be from the head gasket surely???

Can any experienced boat mechanic please assist.
 
Adding oil in horizontal cylinders is not always the best way of testing ring/cyl leakage. Plugs however gives quite a good picture of what is happening inside.
But I only have some 40 yrs of experience(???)
 
Ok, am taking the boat out sunday, will post pics after of plugs. By memory the plug with the low compresssion was white tipped?

Will post pics after Sunday day out.
 
A difference of 25 psi between the highest and lowest cylinder reading is not good. The mention of the white tipped plug isn't good either.

Before running the engine further, chancing further problems, it would be a good idea to remove both cylinder heads in order to inspect the pistons, cylinder walls, undersides of the cylinder heads, and the sealing surfaces of the crankcase (block) and cylinder heads.
 
It is a sad day, pulled the head of, damaged piston & head on cylinder that is low on comp. Have organised a guy to rebuild engine :(
 
Question
Should I replace only the one piston with a oversizie one, and just replace the rings on the other three, or replace all pistons?
 
You may replace and if needed re-bore, only one.
But if other pistons are glazed (polished), replace as well with std size, hone cyl and new rings.
 
If the other pistons are as good as new in appearance after a thorough cleaning, reuse them but install new rings.
 
arzy said:
What would have caused no 1 piston to make contact with the head?
Click to expand...

Likely a piece of the piston ring or even the locater pin for a ring was trapped between the pison and the head. Is it mechanical damage? or did that cylinder run lean and suffer from detonation damage? That would lead to a more melted look. Often that is what happened when you hear about a hole in a piston.

If the piston truley whacked the head, you have a failed bearing on the rod or piston pin. That would be uncommon.
 
Picture175.jpg
Picture173.jpg
 
that looks exaclly like what happend on my dirtbike. bottom end came loose, peace of needle bearing beat the piss out of everything.

by the looks of it, it somewhat looks like a needle bearing was smashing the head.
 
Broken rings!
Have seen it worse!
Just keep on tearing down.
Your biggest 'problem' might be to get the power-head off the leg.
Remember to change impeller and thermostats when PH is off.
The thermostats are not in the PH but on top of the exhaust housing left on the leg.
Will not be surprised if you find STB thermostat stuck open.
 
Thanks for the replies, got a marine guy rebuilding engine. He is saying one piston neeeded oversize 20 thou, use existing pistons with new rings, new thermostats and oil pumps, does this sound right? Do I need to add anything to the fix list???
 
Number one is an OEM workshop manual!!!!
Std needed parts in an operation like this, pistons/rings/bearings not included are complete PH gasket kit, carb rebuild kit (2), thermostats(2) with gaskets and impeller. It might even be smart to change the water deflectors.
Check gearcase for leakage at the same time.
Most important at start up, use 2% (50:1) oil in fuel in addition to the VRO if still connected. If VRO disconnected, double oil in fuel first 5-10 hrs.
Mark on the VRO tank with tape or pencil marker, and be sure it pulls correct amount of oil before eliminating oil in fuel. Do not run engine on idle or unloaded more than needed the first 5-10 hours!
 
Arzy...... DO NOT attempt to reuse that cylinder head. The smallest piece of steel buried (hidden) in that aluminum head would glow like a model airplane glow plug which would result in pre-ignition, which in turn would result in a melted piston etc. You would not want a repeat of the problem.
 
The engine rebuild has begun, the block had to be bored 30 thou on the damaged piston bore. The Crank, Rods, Bearings are all good. The guy rebuilding it has been in the marine business for years. He is replacing the wiring loom, the outer insulation is crumbling off. New Thermostats, impeller. The carbs have had the bowls of and been checked. New Rings on the existing pistons.

What do I need to do to run this engine in? The oil is being replaced with a good quality two stroke oil, and a 100 to 1 in the fuel tank.

Any advice appreciated.
 
Unless you're going to install a "New" VRO pump, I strongly suggest that you convert back to pre-mix using a 50/1 mixture as follows:

(VRO Pump Conversion To Straight Fuel Pump)
(J. Reeves)

You can convert the VRO pump into a straight fuel pump, eliminating the oil tank and VRO pump warning system, but retain the overheat warning setup (and fuel restriction warning if so equipped) by doing the following:

1 - Cut and plug the oil line at the engine so that the oil side of the VRO pump will not draw air into its system. Trace the wires from the back of the VRO to its rubber plug (electrical plug) and disconnect it.

2 - Trace the two wires from the oil tank to the engine, disconnect those two wires, then remove them and the oil tank.

3 - Mix the 50/1 oil in the proper amount with whatever quantity fuel you have. Disconnect the fuel line at the engine. Pump the fuel primer bulb until fuel exits that hose with the tint of whatever oil you used. Reconnect the fuel hose.

That's it. If you want to test the heat warning system to ease your mind, have the key in the on position, then ground out the tan heat sensor wire that you'll find protruding from the cylinder head. The warning horn should sound off.


Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:
http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store

Also, as a reminder....... DO NOT reuse any damaged cylinder heads!

 
Back
Top