Black max running HOT

[Diamond Dave]

I have a 1995 merc 150 black max XRi running hot at idle, It?s a little better when I?m running. New water pump and thermostats. The **** stream seams ok but it gets hot fast, you can barely touch it I?m perplexed. What do you all think? Any help is greatly appreciated. Thanks,

Dave

 

[Dukedog]

Re: Black max running HOT

Complete kit or just impeller? OEM or aftermarket? What did tha old impeller, housing, gaskets and ride plate look like?

 

[Diamond Dave]

Re: Black max running HOT

OEM parts, impeller and housing, everything looked ok. I replaced it about a year ago? Just don?t know. It takes about two minutes to start pissing and it comes out HOT. I mean steaming?

 

[Dukedog]

Re: Black max running HOT

Anytime we have a heat problem we start at tha source. Tha pump. Even if its known ta be "fresh" it can, and more times than not, be tha problem (even brand new). New pump, t-stats and poppet is the best investment you can make on tha motor with heat problems in my way of thinkin'. Changin' one of these things at a time is ok if its a maintance type thing but if its havin' a problem we change all three at tha get-go. Do you have a pressure guage?

 

[Jacket4life]

Re: Black max running HOT

Sounds ALOT like the t-stat is opening at too high a temp, or faily to open completely. That would be my first step, personally.

 

[Diamond Dave]

Re: Black max running HOT

I have access to pressure gauges. What kind of PSI should I be looking for and where is the test port or the best place to check it at? I know its not the thermostats I pulled them off when the motor was hot and they where fully open. Don?t know if this info will help or not but the oil injection system was removed before I bought the motor. I premix 50 to 1

 

[Diamond Dave]

Re: Black max running HOT

I have a SELCO Repair Manual. It tells me ? A high volume pump is used on the 50 to 200 HP lower units? it gives me an illustration but the pump looks different than the one that came off and the one the Merc Dealer gave me. Just to clarify new pump and old pump look the same but different that the illustration in the SELCO Manual ???

 

[Dukedog]

Re: Black max running HOT

There is a hose top center of tha block. It goes down to tha bib on tha poppet. put a "T" in it at tha top to supply tha pressure guage. It kinda sounds like tha poppet is stuck open but its hard ta tell on a computer. Thats why I recomend startin' with new water parts. If that doesn't work ya gotta start lookin' for sumptin' a lot more serious. Lemme know what tha pressure is at idle and wot...........

 

[Diamond Dave]

Re: Black max running HOT

I think I might have a stuck popit valve, can anyone tell me where it is on this motor. Thanks.

 

[Dukedog]

Re: Black max running HOT

Follow tha hose I was referring to. It goes to a bib that is attached to tha poppet assy. right under tha switch boxes. You really need to pull tha lower cowl to get to it. Especially if you have never taken one out..........

 

[Diamond Dave]

Re: Black max running HOT

Thanks

 

[Diamond Dave]

Re: Black max running HOT

Just finished checking the compression, it got pretty hot and I was concerned I might have really damaged it. Thank God it?s got good squeezes 130-140-130-140-145-140 I?m going to install a new poppet valve and see what up. New pump OEM and new thermostats already done so I feel the poppet will do the trick.

Dave

 

[j_martin]

Re: Black max running HOT

I have a SELCO Repair Manual. It tells me ? A high volume pump is used on the 50 to 200 HP lower units? it gives me an illustration but the pump looks different than the one that came off and the one the Merc Dealer gave me. Just to clarify new pump and old pump look the same but different that the illustration in the SELCO Manual ???

There is a high volume and a low volume version of the pump. Yours uses the low volume high pressure pump.

Discard the Seloc manual and get some decent reading material.

 

[DaleBurris]

Re: Black max running HOT

There is a high volume and a low volume version of the pump. Yours uses the low volume high pressure pump.

Discard the Seloc manual and get some decent reading material.

So if you used the low volume pump would that create overheating at idle?

 

[Diamond Dave]

Re: Black max running HOT

There is a high volume and a low volume version of the pump. Yours uses the low volume high pressure pump.

Discard the Seloc manual and get some decent reading material.

Yea I?m not real impressed with the SELOC manual. How can I be sure I?m getting the right pump? The dealer looked it up by the serial number.

 

[Dukedog]

Re: Black max running HOT

I doubt you got tha wrong pump. V6 pumps are pretty generic. Did you hook up a pressure guage? If tha poppet is screwed up your not gonna have enough pressure or volumn at idle..........

 

[Diamond Dave]

Re: Black max running HOT

I haven?t yet; I?m going to replace the poppet regardless. Unfortunately I have to go in to the office for a bit on Saturday but I will make repairs Saturday afternoon and go run her on Sunday. I don?t really like running it on the hose, I don?t believe you can get an accurate result because you?re forcing water past the pump up through the driveshaft housing etc. I?d rather have it in the water with the pickup submerged.

If I understand correctly, on this motor because it?s EFI it needs to run at a higher temp than the carbureted 2 strokes. The thermostats open at 140 ish and then it starts pissing. I will bring my laser thermometer and check the head temp at that point. If all is good at idle I will go and make a couple of high speed passes. Help me out with this. If the poppet is stuck open you can run hot at idle and if its stuck closed you can run hot at speed/higher RPM Is that right?