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1994 Merc 74L 454 rebuilt recently again

T

Tom Ambrosio

Guest
"Long story short! Bought a 94

"Long story short! Bought a 94 Searay BR 7/07. Sat for 2 years prior with 10 hrs on rebuilt engine. Impeller was replaced at purchase. Ran great til overheat 9/07. Blew 5th cyclinder and piston. Same engine rebuilt over winter. Back in business 7/08. out a few time so far. Circpump, tstat and fuel pump are new "supposedly".

Here is my problem. In slip, temp runs at steady 170ish. While moving, jumps from 200 down to 100 than back and forth. Never seeme to pin at 220, but jumps all over the place. Afraid to run, don't want a rebuild again. Was told I should be able to keep my hand on the risers and manifold without burning. I cannot.

Any thoughts? If I were truly overheating, wouldn't gauge pin at 220?"
 
Insufficient water flow underw

Insufficient water flow underway. Are the temp changes slow or like flipping a switch? Start w/a new impeller.
 
"not like a switch when increa

"not like a switch when increasing, but pretty fast when dropping to 100 deg. Impeller is "supposedly" new in mid july. Could the impeller go that fast or have I been robbed again? I will check over the weekend when i get down to the boat. Am I correct in saying that there is no pump componants in the drive? The sea water pump pulls the water through the holes on the lower unit through the hose through the housing, correct. Also, just repainted the drive and made sure holes were clear. Not sure if I am using the right description, but when i feel the hose flowing into the tstat housing, I feel turbulance. Should this be a solid flow? I am assuming yes! Just had a friend lose an engine due to restricted waterpickup from barnacles inside the lower unit ("welcome to the Jersey Shore"). That is what led to my drive componant question."
 
Check your water intake points

Check your water intake points for barnacles. They may be in the water intakes. Also install a clear water hose at the T'stat hsg. to see if there is air in the line.

Water impellers will fall apart quickly w/o sufficient intake water to pump; don't think you were ripped off.
 
"Thank you. Extremely happy I

"Thank you. Extremely happy I found this site. After reading some threads, It's nice to know that there is a place to get helpful, knowledgable info. I look forward to being here often.
Is engine actually overheating or am I getting a false reading. If I was overheating, wouldn't guage pin at 220?"
 
tom ambrosio
Get yourself an

tom ambrosio
Get yourself an independent heat gauge or or an IR thermometer gun and make sure you really have a problem before tearing into it.
Bert
 
"Bert,

Thank you. The lea

"Bert,

Thank you. The least time ripping and more time cruising, the better. Where is the best place to find a gun? I've never replaced an impeller, pretty mechanically inclined so i'm assuming I can pull it off? Getting a tech this time of year for a small job is like pulling teeth!

Thanks again!"
 
"Your boat draws its water thr

"Your boat draws its water thru the bottom of the boat and the inpeller in attached to the front of the engine similar to you altinator.

This sound to me like your thermostat is malfuctioning. Could be something floating in the housing.
Irratic changes like that seems to me would indicate (assuming gauge is working correctly) that you are getting a sudden opening and closing of the thermostat.

Remove the thermostat, inspect housing for foreign matter or anything that may look corroded leave the thermostat out and restest. If the temps stay nice and cool and STEADY then replace it!

143 degree t stat."
 
"Tom Ambrosio
Not too familia

"Tom Ambrosio
Not too familiar with the US tool outlets. I bought mine from Snap On when they were just out and high in price. I imagine any place like NAPA or Sears would have them. They're a great tool around the house, boat and garage.
Regards
Bert"
 
"Tom;
You can pick up an IR t

"Tom;
You can pick up an IR temp gun at any Napa, AutoZone, etc.
The Bravo has no pump in the leg. The pump is belt driven low on the stbd side typically, and can be a real b!tch to get to.
There are two common water pickup systems used bith Bravos, and you will have to do some research to find out what yours has.

The most common is thru the leg pickups holes, and all the advice given above applies.

The second method is using a thru-hull pickup as KG said. In this case you need to check the pickup holes and the sea strainer for crud. This will involve pulling the boat out of the water.

Regardless, if the pump is not getting enough water, you could easily have fried the impeller, and I would at least pull the pump and inspect it.

If all is working well, you should have risers cool enough to keep your hand on them. 120-130 F should be tops. The exhaust manifolds will run hotter at 180-190, if you are using a 160 stat.

Rod"
 
"I am told it is a new 160 tst

"I am told it is a new 160 tstat. I should be able to get to the boat Saturday. I will look at all info given by everyone who responded. Thank you, you have all given me extremely helpful information. It's getiing hard to find someone you can trust with your boat nowadays! I try to do as much as I can by myself.
Thanks again. I will hopefully have an update by Sunday or Monday.

If I can find a clear hose, should I bypass the oil/steering cooloers or just go from them to the tstat housing."
 
"Tom;
You only need a short l

"Tom;
You only need a short length of clear hose to determine how much air is in the water. A foot or so will do it, so any convenient location will work. You could run straight from the pump discharge to the stat housing.

BTW; there is a braided clear poly hose used for various RV services that comes in 3/4" and 1" sizes at least that works well for this purpose. You may need 1-1/4"

Rod"
 
"Thanks,

As I said in my fi

"Thanks,

As I said in my first or second post, When I grasp the hose going into the tstat housing, I feel turbulance. I am assuming that it should be a more solid unrestricted flow. After listening to you guys, I have a few things to check. First, I will check the Tstat housing. When i run it at the dock, pressure seems weak from tstat to circ pump. If tstat is closed, flow should be weak to none, right? However, the turbulance on the input side tells me my problem is prior to the tstat. i will also check the path from pump to tstat. The tech who rebuilt it said the seawater pump was perfect and that he replaced impeller. That will be my next check. If I open the pump up, I may as well replace it anyway, right? Will I need the whole rebuild kit or will a gasket and impeller be enough?

Really appreciate your time and info."
 
""I grasp the hose going i

""I grasp the hose going into the tstat housing, I feel turbulance"

Hoses wear from the inside out. Rough internal surfaces will create turbulence; how much, not sure."
 
Thanks! Another good thought.

Thanks! Another good thought. Hoses look ok but not sure how old they actually are. There is another check added to my list. Gonna be a long weekend! Guess it beats working!!!!!
 
"While you are at it, verify t

"While you are at it, verify the oil coolers don't have barnacles or impeller chunks lodged in them; impeller chunk debris is very common."
 
"I would sure change the pump

"I would sure change the pump impeller anyway, as long as you are in there. Right, impeller and gasket should be about it.
If the old one looks good, keep it as an emergency spare.

Not sure that turbulence in the inlet hose is all that significant. The main inlet hose flows up to 35 gpm of water, and in a small diameter hose that is going to feel turbulent through a relatively thin rubber wall. It may not mean that there is air in the line.

From the stat housing the water splits into several smaller streams, so none of them are going to feel all that turbulent. The circ pump inlet hose will have low flow unless the stat is quite wide open, so its not a good comparison.

Let us know what you find.

Rod"
 
Well this is what I know..&#40

Well this is what I know..(and that aint much...LOL)

I recently had a 27 ft cig style boat with a 454 and a bravo 1 that a friend bought and wanted me to do a once over.

Well that once over has turned into a 3 year one thing after another and many thousands of $$$$.

The first thing I did was have to pull the engine.
remove the transom assembly due to a cracked gimbal ring. While working on this where the water hose from the outdrive passes thru the transom the hose is not secured by hose clamps but rather it is "sqeezed" in place by an threaded collar. Well the passage at that point was 3/4 restricted with the white oxidzation biuld up typically cause by salt water or what ever. I was very surprised at the amount of water resrtiction that this would cause. The boat owner never used the boat so I can not say for sure what it had done or would have done if he had used it before I was able to work on it.

So if your boat has been is a brackish or slat water enviroment I would suggest looking at what I described.

Good luck.
 
Kg;
Incredible; who would hav

Kg;
Incredible; who would have thunk it?
Boats are packed full of surprises. Unfortuately most of them slam you in the wallet!

Rod
 
"Well All I have to say about

"Well All I have to say about that is


WHEN BUYING USED TRY TO BUY ONLY FRESHWATER USE ONLY BOATS. Less headaches and assemblies tend to come apert with hand wrenches not with accedylne gas wrenches if ya know what I mean.

Salt water no matter what the boat manufactures try to do takes its toll!!!

MAKE SURE IT RUNS AND RUNS GOOS BEFORE BUYING IT.

IF YOU DONT KNOW HOW TO FIX IT OR CANT AFFORD TO FIX IT,
THINK TWICE.

Any boat can have problems. The results as to who next has the problems is normally due to neglect or someone who tries to do repairs without any training or experience. IE: car mechanic working on boat repairs. Engine machanics sure but outdrives and ingintions. No way not without service manuals and some training and special tools.

Just my honorable opinion....JMHO"
 
"got to boat briefly on Sunday

"got to boat briefly on Sunday. Didn't have much time!

pulled hose from oil cooler to steering fluid cooler, found 5 or 6 strands of seaweed (welcome to Jersey). When rolled into a ball it was about the size of a nickle.

Flushed from tstat housing back to fluid cooler. Nothing else seemed to eject. I checked the intake to tstat housing opening and no debris or even discoloration was found.

I have a fresh water flush in transome and followed that to a tee about 16-18" from seawater pump (toward oil cooler). removed hose and found no restrictions.

Did not have time to tackle pump and impeller, But did run the engine for about 15 minutes. Ran a steady 165-170 degree when warmed up in slip.

Question: I never actually overheated. If my impeller was shot wouldn't i overheat and stay that way from the point of warming up?

#2 if the freshwater flush is not airtight at the transome, could air be sucked in while running the engine. i would assume that there is some sort of baffle in the tee that connects the flush line. The flush connection at the transome is a simple female connection with a screw on cap. The engine did not have this gause fluctuation before rebuild this fall/winter/spring.

I will tackle the pump this weekend depending on the answer to above impeller question. Also will sea test to see if guage jumps.

Could that little bit of seaweed be enough to screw me up?

Thanks guys, I will update more as I progress"
 
One boater just found his runn

One boater just found his running hot problem. It was the water inlet hose; it had deteriorated to a point that it nearly closed off water circulation. Check them all by squeezing them w/your hand. If you find a soft spot on a hose replace it.
 
I think it was a Bravo pump ho

I think it was a Bravo pump hose to a diverter.

thread: "White smoke from exhaust"
 
"fINALLY MADE IT BACK DOWN SHO

"fINALLY MADE IT BACK DOWN SHORE. gOING TO TEST BOAT IN AM. One thing i have been thinking about by evaluating feedback and other links. The boat has a fresh water flush in the transom. I traced the hosew from the transom to the pump to cooler hose. It has a plastic tee. There are no restrictions in the tee that I can see. Is there a flapper inside that tee. Could air be getting sucked in from there. It doesn't make sense to me that the temp gauge fluctuates when running only. As I said before, i did find some "jersey shore salad" prior to the fluid cooler, but was only able to run the boat in the slip.

I think I am going to have to pull the boat and look downstairs in the unit if the gauge fluctuates tomorrow.

I'll update tomorrow."
 
"Update with no fix yet.

We

"Update with no fix yet.

Went to boat today:

ran boat and same problem was there. Fluctuating gauge when running, not in slip.

cleaned connections(slip-on) to sending unit for tstat and alarm sensor. Weird thing is that alarm sensor and sending unit are switched in tstat housing. Grounded each out and the gauge worked. Apparantly, the buzzer does not work.

when i moved wire on alarm sensor, which I thought was sending unit, guage went to 100'.

Replaced sending unit and cleaned wires. Left unit and sensor in the holes they were in.

Checked all hoses including tee from fresh water flush in transom. found a few things of concern.

1. hose from pump to tee in flush has a clamp that looks like it was crushed while putting engine back in and salvaged and reused. Not sure if air is getting in. will replace tomorrow. Marina tech says he has seen those tees crao out over time and let air in.

2 guy who rebuilt my engine "this time" says I got a new circ pump. hose from tstat housing to circpump or visa versa is about 5" and is not pre formed looks like may be restricting flow from pump to housing. should that hose be an elbow or haa anyone seen a regular hose bent to fit.

Im running out of ideas!!"
 
"Tom:

Sounds like your &#40

"Tom:

Sounds like your (lower)thermostat housing doesn't have the copper(?) grounding lug in it. You can check the gauge and the wiring by removing the lead from the sender & connecting the lead to one end of a 100 to 110 ohm resistor (radio shack). clip the other end of the resistor to ground. Key on and the gauge should go about 1/2 way.

The warning horn should sound with the key on - engine off - due to the oil pressure switch grounding the horn. If that doesn't work, horn is bad, the leads from the switches to the horn is open, or the +12 from the key is open. It could be the horn is bad too. You can check it direct, just like a light bulb - remove the leads to it first. Typically, the oil pressure switch and the overheat switch are paralleled - any one of them can turn on the horn"
 
"makomark,

Thank you. Wher

"makomark,

Thank you. Where does the lug go? Is that part of the sleeve? I noticed in the manual that you are not supposed to use adhesive on the lower gasket for, i believe, grounding purposes. something about a meterial on some gaskets. I did not do the work on the engine and have not removed the housing yet. Probably will tomorrow. Does the flush hose issue sound like it could be a problem to you?

thanks again"
 
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