150 XR2 steam out of the exaust.

[J Hartman]

Noticed that I have some steam coming out of the exaust of my engine. I would have to say it's quite a bit more than normal. If it is "normal" Did these engines have problems with head gaskets? What would be the cause of this issue? What could be the damages? Just got this ole' engine running, I don't want to have a cylinder meltdown cause of water in the pistons.

 

[j_martin]

Re: 150 XR2 steam out of the exaust.

They'll steam if water delivery is not up to par. That could be at idle if the poppet is stuck open.

Pull the plugs and peek in. If it's normally dirty, you're OK, Squeeky clean cylinders and plugs indicate water intrusion.

hope it helps
john

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

They'll steam if water delivery is not up to par. That could be at idle if the poppet is stuck open.

Pull the plugs and peek in. If it's normally dirty, you're OK, Squeeky clean cylinders and plugs indicate water intrusion.

hope it helps
john

I may win the idiocy award for this... What is a poppet?

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

Also, I feel the need to check on the state of the impellar now. . . Which way do you have to spin the impellar when placing it back into the housing? clockwise or counter? When looking down at it in the lower unit?

 

[Chris1956]

Re: 150 XR2 steam out of the exaust.

Turn the driveshaft clockwise to install the impeller into the housing. Test or replace the thermostats. Rebuild the poppit valve. Poppit is located at the base of the block on the starboard side of the block. Rebuild kits are avail.

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

I have replaced the thermostats on both sides. I am still not understanding what the poppit does. I found where it is located on the Mercurypartsexpress.com but. What exactly does it do? I'm not understanding it yet for some reason.

 

[sschefer]

Re: 150 XR2 steam out of the exaust.

The poppet valve is a pressure relief valve. It has a spring with a predetermined tension. When the water pump begins producing enough pressure it will open and allows more water to flow through the engine. It usually begins to open at around 1800 RPM or 6-8 PSI of water pressure.

It takes over for the thermostats which, if the engine is running at a normal 140 degrees, should be closed and only allowing water to escape via their bypass holes.

 

[Faztbullet]

Re: 150 XR2 steam out of the exaust.

Is the steam comming from "pisser" or exhaust ports below cowling???

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

I noticed it originally coming out of the exaust ports under the cowling. pretty heavily. The pisser steams as well... I believe the water that comes out of the pisser is WAY too hot as well.

 

[sschefer]

Re: 150 XR2 steam out of the exaust.

This may seem like an odd response but it may not be cooling system related at all. A lean condition will produce higher than normal at idle temps. It can also be accompanied by a higher than normal idle RPM but not not always and may have been compensated for during a routine tune up if that was done recently.

You'll need to put a fresh set of plugs in it to read them correctly. Once done, run it at idle until the steam begins to develop and then shut it down and pull the plugs. You need to closely examine the plugs because at first glance they may look all the same. If you have one or two lean cylinders, the plugs will show a slight amount of tan on the porcelin around the electrode. The other plugs should be somewhat wet.

If you see anything different at all in the plugs, then you know your on the right track. If not, then go back to the cooling side of things.

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

these are the "flat" plugs. Will i still be looking for the same symptoms?

 

[latin monkey]

Re: 150 XR2 steam out of the exaust.

yes

 

[sschefer]

Re: 150 XR2 steam out of the exaust.

these are the "flat" plugs. Will i still be looking for the same symptoms?

Yes, that's why I say it'll be hard to read them so study them close.

 

[Faztbullet]

Re: 150 XR2 steam out of the exaust.

I have never see one get hot at idle due to a lean condition, they just wont idle if that lean. Everybody likes to blame "poppet" or t-stats but the most common cause I see are debris in divider plate(dirt dobbers) and warped or improper water pump housings and gaskets. Salty /brackish water is different story... The water flow on a V-6 (pre 89) comes from impeller to center of block, out thru divider plate (cools exhaust chest 1st) around cylinders to stats then poppet. I see your close by, pm me and if real close will take care of it for ya

 

[CharlieB]

Re: 150 XR2 steam out of the exaust.

A small amount of steam coming from the exhaust vents is normal, however, steam from the P stream is a sign of a serious problem.

Is the P stream overly hot/steaming at an idle? Or is this beginning to happen at larger throttle opening when in gear?

Leaking head gasket(s) often will not cause overheating/steaming P stream at idle or light loads, but once load increases then cylinder pressure overcomes the gasket, leaking combustion gases into the cooling system, displacing cooling water then the engine begins heating to the point the P stream steams.

A warped water pump housing can also cause this condition, as the pump is submerged and pumps fine at idle and slow/low speeds, but once the boat comes up on plane the gearcase sits higher in the water and the pump is no longer submerged and begins to suck air, reducing cooling.

Lastly, ignition timing, retarded ignition timing will cause engine heating under throttle, yet seem fine at idle. A proper link and synch to check WOT timing should also be done just to be sure that all is set correctly.

 

[sschefer]

Re: 150 XR2 steam out of the exaust.

I have never see one get hot at idle due to a lean condition, they just wont idle if that lean. Everybody likes to blame "poppet" or t-stats but the most common cause I see are debris in divider plate(dirt dobbers) and warped or improper water pump housings and gaskets. Salty /brackish water is different story... The water flow on a V-6 (pre 89) comes from impeller to center of block, out thru divider plate (cools exhaust chest 1st) around cylinders to stats then poppet. I see your close by, pm me and if real close will take care of it for ya

I have never see one get hot at idle due to a lean condition, they just wont idle if that lean.

True and False. You probably have never seen one (true) but they will idle fine if the timing is compensated.

 

[Faztbullet]

Re: 150 XR2 steam out of the exaust.

You would have to have the primary pickup screw turned nearly all the way out to cause timing to cause a overheat at idle due to ATDC not BTDC, real hard to increase combustion temps ATDC.

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

The main instance in which i noticed the heavier steaming(out of upper exaust, under the cowl), was after a run on plane, (not WOT) and then slowed it back down to idle. That is when I noticed the heavy amounts of steam in the first place. The P stream steams almost at all times. after the engine has ran for a few minutes it is too hot to leave you hand in the stream.

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

I think I'm going to begin the repair by doing this...

1st - Remove spark plugs, check for any abnormally clean plugs (caused by water intrusion)

2nd(a) - If clean plugs are found, remove the heads, and replace head gaskets, cleaning any trash within that i might find.

2nd(b) - If no clean plugs are found I will begin the process of dropping the lower unit. for 2 reasons. 1. To replace impellar, gaskets, and housing, and 2. to remove T-stats, and attempt back-flushing of the system to see if any kind of debris or trash comes out.

sound like a good plan?

What do I need to know about removing the lower unit on this engine?

 

[J Hartman]

Re: 150 XR2 steam out of the exaust.

also step 1 1/2 - Compresssion check for low PSI in a cylinder which may represent a leaking gasket.