88 XR4 - Gotta be the Poppet valve, Right?

Musclford

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Jun 28, 2004
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ANY IDEAS? We took it out for the first time of the season and we were heating up and peeing very little or not at all. Can't remember:) We tore it down to put in an impeller but we had to buy the whole water pump housing as ours was distorted and didn't look good. <br /><br />When we started it up on the muffs, we get no water peeing? Nada, nothing... I can feel air being pumped out the water discharge, but no water. Temp gauge started to come off of "C" so we got worried and stopped. Pulled it apart and rechecked everything. Still same results even if we goose the throttle. I had just remembered that where we put the boat in last it is very shallow and very silty. Maybe it clogged up, but we haven't found any silt or dirt in the lower end components?<br /><br />Also, in our manual it states we should check the shim clearance between the bearing in the lower unit and the pump housing. We didn't as this looks different than that explained in the 86 V6 manual we have. I figured this is a tad different as it was an all new engine in 88. <br /><br />Anyone have any suggs. Kinda worried our motor has other probs? Could the thermostats be stuck? But both of them and the old impeller wasn't shredding or anything so I can't believe it is plugged with something. Should we pull out the thermostats? <br /><br />Thanks in advance, we anxiously await your replies..<br /><br />Thanks<br /><br />Phil
 

Laotzu

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Aug 1, 2004
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150
Re: 88 XR4 - Gotta be the Poppet valve, Right?

Last week I drifted into shallow water and churned up some mud getting out to blue water.. Same as yours, no pee. I took it home and put the muffs on and ran the water on high without starting the motor. Cleared it up after about 5 minutes. The water under power never reached the pump or thermostat. Worth a try.<br /><br />Jerry
 

WillyBWright

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Try blowing some compressed air into the pee hole. It could be clogged. Go ahead and check your thermostats. If they're scaled-up, a good soaking in vinegar will take care of that. You shouldn't have to worry about the shims. You may not have the gearcase the manual is describing. There have been several versions. But even so, tolerances are pretty tight on the components you replaced, so reshimming shouldn't be an issue.
 

KCLOST

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Jun 22, 2002
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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Check the poppet valve.... If it is stuck open you will be dumping water from the block at lower rpms (under 3000) and cause higher than normal temps. And very ittle water will be left to circulate around the block (again at lower rpms)...<br />This is my bet....
 

Musclford

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Yep, after our last test, I'm thinking it has to be something other than the water pump and thermostats. I hooked up a hose directly to the tube where the water pump is. Turned it on slow and won't get anything out of the pee hole and water kept comming back down the exhaust part of the lower unit. <br /><br />Turned up the water faster and finally got it to pee. So I'm thinking that according to the manual, the poppet valve is probably ruptured, letting water by at low pressure. <br /><br />NOW, what am I getting into by doing this myself? My dad is an auto mechanic for 35 yrs. Just never done anything to an outboard other than normal maint and of course the water pump.<br /><br />Is this common? Looks like it is on the bottom of the power head. Right?<br /><br />Thanks
 

KCLOST

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

It's so easy to check! No problem at all...<br /><br />It is located under the switchboxes on the starboard side of the engine block, down low... It has a egg shaped or "8" shaped cover held on by a few bolts.... Pull it and clean it out if dirty... and ispect the diaprham, spring, grommets etc....<br /><br />Here's a link to view...<br /><br /> Poppet
 

Musclford

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

KCLOST,<br /><br />I answered my own question. Mine didn't have the hose going to it like the manual showed. It looked like it was located underneath. Anyway, took off the cowl and it was staring at us. <br /><br />Pulled out the 4 bolts, took out the screw and wouldn't you know we found a rock about 1/8" in size. Unfortunately we tore the gaskets so now we have to wait for parts until we can confirm this was the problem. Sure learned alot about our cooling system though. <br /><br />We're going to buy 2 thermostats and gaskets. Would you recommend replacing any of the poppet parts, less the gaskets?<br /><br />Thanks alot,, I really think this was are problem. To think we had that lower unit off 6 different times. even went as far as turning the drive shaft by hand while it was off the boat and on muffs to see if the pump was pushing water. <br /><br />Oh Well... <br /><br />Is the link a good affordable place to buy outboard parts? Or should we just go to the local marine shop?<br /><br />thanks alot!!<br /><br />Phil
 

KCLOST

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Good to hear.....<br /><br />I'd just go to a Merc. dealer to get them... The gaskets are cheap... If everything else looks good... I'd leave it alone...<br /><br />I bought everything for a total replacement, except for the cover and divider plate, for around $35, if I remember correctly...<br /><br />Is there a hose fitting on the small circular part of the cover, or a threaded hole in that same area?
 

KCLOST

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Also, I'd pull the stats if you haven't already and check for blockages there....<br /><br />It ain't over yet, but you may have found the culprit....
 

Musclford

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Re: 88 XR4 - Gotta be the Poppet valve, Right?

Originally posted by KCLOST:<br /> Good to hear.....<br /><br />I'd just go to a Merc. dealer to get them... The gaskets are cheap... If everything else looks good... I'd leave it alone...<br /><br />I bought everything for a total replacement, except for the cover and divider plate, for around $35, if I remember correctly...<br /><br />Is there a hose fitting on the small circular part of the cover, or a threaded hole in that same area?
No I didn't see any hose / threaded hole near by.<br /><br />We did pull the thermostats and they looked good, but will replace them since they are 16 yrs. old.<br /><br />Thanks again for your advise.. I think we'll be throwing rooster tails again real soon...<br /><br />Phil
 
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