Logo

1980 Mercruiser 260350 Engine overheating

pat609

New member
"Hello everyone,
I'm new


"Hello everyone,
I'm new on this Website,so I hope I'm following posting rules,I posted same message, but I believe in the wrong place unable to delete it.Just purchased 1980 Silverline inboard with a Mercruiser 260 hp V8. (Chevy).Test drove it for about 1 hr in river,ran great temp. at 160.Took it to lake yesterday for first time
did just fine,stopped for about couple of hrs to fish.While going back to dock (not at full speed) engine overheated to 240 and stopped running waited 'till engine cooled and finally made it to launch, engine again overheating,checked belts all intact at that point oil pressure was low. I used the garden hose today oil pressure back to normal,pulling water but don't know if its letting it out.Never owned a boat before have no idea where to start.Any suggestion greatly appreciated."
 
"The drop in oil pressure is m

"The drop in oil pressure is most likely due to the high temperature of the oil while the engine was overheating. Not a big deal, might want to consider an oil change in the near future, but as long is doesn't smell burnt, it should be fine.

What kind of sterndrive (Pre-alpha, alpha, bravo, etc.)?

When you ran it on the garden hose, was any water coming out of either of the two idle ports (located on the transom plate on the outside of the boat) or out through the center of the prop along with the exhaust?

Is the engine freshwater or raw water cooled? (Is there a place to add engine coolant, like a small reservior?)"
 
I'm a novice at this how d

I'm a novice at this how do I determine the type of stern drive I have? i found the following # on front plate of O/D 5248932 1.50R
There is no place to add coolant so I believe it to be raw water.I tested the thermostat and it opened.Thank you.
 
"Troy & Pat:

Pat, as a


"Troy & Pat:

Pat, as a new boater Troys advice for an oil change is good advice. Just use a (here we go again on the oil issue) quality oil. Mercruiser recommends 25W40 Wt. oil which they are the only dealer I have found that sells that wt. I use a 15W40 Shell Rotella oil while others like synthetics such as Mobile 1 in a 15W40 or 20W50 wt. Your choice; just use a quality filter.

Overheating on the lake at low RPMs, if Raw Water Cooled (RWC), sounds like the impeller in the OD is worn and needs replaced or you may have sucked some trash into the water inlet on the OD. Thermostat may also have not opened.

If Fresh Water Cooled (FWC), your raw water pump may be worn, heat exchanger may be plugged and needs serviced.

If it does not overheat on a garden hose, that is because the water hose pressure is making up for the weak impeller. Thermostat is probably working if the temp is stable."
 
"Pat,
The best advice I can g


"Pat,
The best advice I can give from this point forward is to buy the service manual shown on this site, or the equivelent, even if you don't intend to service it yourself. The information in the first few chapters, plus the exploded view pictures in the rest of the chapters will help you understand how things are supposed to work so you can quickly recognize when they aren't working the way they are supposed to be. When you come here for help, we'll all be speaking the same language, things will make more sense, and we'll be able to get to the bottom of your problems alot faster.

So, when you ran the engine on the garden hose, where did the water go in, rabbit ears on the outdrive, or somewhere else? And, where, if at all, did the water come back out? Was there steam instead of water coming out?
If nothing came out, we're going to have to figure out where it's going."
 
"Did a little digging on that

"Did a little digging on that serial number, guess this is the oldest one I've looked into. It's a pre-alpha drive and that '260' refers to the model of the drive as well as the HP rating of the engine.

There is a small rubber impeller (water pump) driven by vertical drive shaft. They wear out and sitting idle for a long time doesn't do them any favors either. When they get old, they crack and the rubber flingers break off.
Two issues:
- No cooling water flow... engine overheats.
- The little flingers chunks may get stuck somewhere in the system.

Like Guy said, the pressure from the garden hose is enough to overcome the fact that there is no pump. Since it ran without overheating is fairly encouraging and would indicate that any broken off chunks went all the way in and back out through the exhaust.
First step is to replace the impeller, which involves seperating the lower unit from the upper unit to get to it. Not a difficult job, but this is where the book comes in handy."
 
"Troy,Guy,
Thanks for all you


"Troy,Guy,
Thanks for all your help.I'm going to get the book .Mean time I tok an other look @ the add by the guy who sold me the boat, it states the following were just installed within a year "The outdrive has had a new waterpump, gaskets, & service recently as well as a new engine coupler installed by a marine repair shop". Going to use the hose again just to make sure that water went in and out as it should,no steam at all Thank you"
 
"Pat:

Let's assume the


"Pat:

Let's assume the impeller was replaced as stated by the previous owner and it is capable of pumping water. The water is drawn thru the lower leg water inlets by the pump and sends it up the inside of the OD to a rubber water hose that attaches to the gimbal. A pass-thru tube connects to another water hose on its way to the thermostat housing as it passes thru an oil cooler.

If you have a large tub that you can lower the OD into and fill with water, you can test the impeller at home. A heavy duty box lined with a heavy duty trash bag will also work. Remove the prop if necessary. Keep a garden hose filling the tub or box.

With a cold engine remove the hose attached to the T'stat housing that I described and hold it over a bucket and start the engine. ONLY RUN THE ENGINE FOR NO MORE THAN 30-60 SECONDS. Within a few seconds the hose should be pouring out water. If that is working the pump and plumbing is good to that point.

There should be a large "T" on the T'stat housing with a hose on each side. These hoses send cooling water to the upper part of the exhaust manifolds. Remove the hoses from the "T" and inspect the check valve balls on each side. They are spring loaded and should move freely. They prevent cooling water from being pushed backwards by the exhaust.

There are two more hoses on the T'stat housing that send cooling water to the lower part of the exhaust manifolds. Remove them at the T'stat and check that the outlet tubes are not plugged with rust and crud.

The only thing left are the exhaust manifolds and risers and the flappers or water shutters in the tops of the exhaust "Y" tube. The manifolds and risers will become restricted with rust and exhaust byproducts called crud. They should be removed and soaked in muriatic acid for 1.5 hours and cleaned with a stiff brush; then reassembled.

The last bastion of cooling water barriers are the flappers or water shutters inside the top of the "Y" pipe on each side. Remove the rubber exhaust from the "Y" pipe and examine the shutter or flapper. It is a rubber coated valve that closes off the exhaust temporarily when there is a backwash at the stern from your sudden stop at 4500 RPMs. The flapper/shutter can rot away and fall into the "Y" pipe thereby restricting the flow of exhaust and cause an overheat condition. The following site lists the parts of your engine with drawings.

http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=79202

Select the item you wish to view and click on it.

This page shows the exhaust flapper or shutter
which is item 19
http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=%2079202&ivar=images/CRUI SER/79202/15.png&inbr=990&bnbr=70&bdesc=THERMOSTAT+HOUSING"
 
"Guy,
Thank you for having ta


"Guy,
Thank you for having taken the time to post.
Couldn't have found better instruction even in a book.I'll have to wait 'till the Weekend ,but I will give it my best shot,and with some luck I will have this boat back in Lake Erie the following wk.Will keep you posted."
 
"Pat:

My pleasure. What po


"Pat:

My pleasure. What port are WE leaving from and are WE after perch, walleye or both? I am retired you know (only 56) and just 3.5 hours from Port Clinton. Just kidding. Enjoy."
 
"What about zebra mussles from

"What about zebra mussles from the lake? Ask the previous owner if he kept it on the water. If you look at the outdrive there will be evidence of them being scraped off.

Those European imports came from ballast water in their freighters along with the Goby, the pesky little fish has fattened up the smallmouth bass population but are also bait thieves.

I live in SW Ohio and fish Brookville Lake in Indiana. The Zebras have invaded that lake too. I can be trolling or drifting and think I have a hit and haul in a cluster of Zebras.

The only good thing about them is that they clean the water of excess algae. Look how clear Erie has become in a few years."
 
"Guy,
The previous owner clai


"Guy,
The previous owner claims to have owned the boat for 2 years,kept it in an outside storage.Last time he used it was April of this year.I bought this Silverline on Ebay, when I met the seller he seemed to know as much about the boat as I....
We live in Maumee, NW Ohio.Took the boat in the Maumee River and it was great!;What happened later is anyone's guess,but I did catch some nice perch!!"
 
I have fished the walleye run

I have fished the walleye run on the Maumee across from Sidecut Park. Maumee is a nice little town. I usually stay w/my sister-in-law in Perrysburg just up the street from Ft. Meigs. That water is cold in March. Where do you put in on the Maumee? I took my 19' Baretta out at the mouth of the Maumee all the way to the lighthouse 2 years ago--3' waves kept me at 10 mph and only caught 2 perch in July. Saw some 8+ lb. w'eyes come out of the Maumee and a few guys go under with waders stepping into deep holes. Good luck.
 
"Fished there many times! Can

"Fished there many times! Can walk to it from my house. Took the boat to the river 2 wks ago just to test it out the day of the purchase,but If I can get it going again it will only go in the lake.I'm planning to work on the boat tomorrow "keeping my fingers crossed".Enjoy your retirement,not too far from it my self"
 
"Guy,
I was finally able to


"Guy,
I was finally able to work on the boat last Sat.:I first checked the impeller and it looks to me to be new,I then submerged OD in bucket and it first all seemed well but within few seconds it stopped pouring water,turned off the engine ,restarted and same issue... I checked for worned parts but couldn't find a thing.I now have the book you mentioned, can't get back to it 'till next Sat.but will keep you posted.Have a great one!"
 
"Pat:

"stopped pouring


"Pat:

"stopped pouring water" from where? If it was the hose to the T'stat, then the problem is from there back to the impeller. Your oil cooler may be plugged with crap or the water inlet hose on the OD may be kinked and/or collapsing."
 
"Guy,
more bad news:decided t


"Guy,
more bad news:decided to take a real good look and also closely listen to the engine ,there is a definite KNOCKING ,low oil pressure and the knocking is constant.I've given up trying to service it myself,will take it to a shop tomorrow ,then decide whether to have it fixed or sell it as is and take the loss.Thank you again for all your help"
 
"If you bought it via eBay; fi

"If you bought it via eBay; file a complaint and if you know where the seller lives, I would get a cop friend in uniform to go with you and demand my money back; it scares the hell out of some people thinking they are under arrest."
 
"Guy,
Had a retired boat mech


"Guy,
Had a retired boat mechanic take a look at the boat,he believes that the knocking is caused by damaged rod bearings,he wouldn't be able to do anything,but recommended a marine shop.Yesterday I took the boat over there
should they come to the same conclusion,I will try to get the money back,the problem is going to be: proving that the seller was aware of the issue ,if not I'll have to sell it and take the loss, a rebuilt engine would cost more than what I paid for the boat.Will keep you posted ,if nothing else I hope my experience helps someone else.Thanks"
 
"Pat:

I am not an attorney.


"Pat:

I am not an attorney. Contact eBay and the seller via certified mail expressing that he did not disclose the true condition of the boat, specifically the condition of the engine and request your money back. If you used PayPal or a credit card you should get some action.

If you bought it in Ohio you may be able to file a claim in small claims court. I don't remember the $$ limit. The seller will be subpenoed to appear in court. If he doesn't show up, you win by default. Then file for a court order for him to pay. If he doesn't pay up, I believe the court would find him in contempt. Check with your attorney.

It has been 10 years since I used small claims. I was paid with a check, deposited it and then they stopped payment; they were 200 miles away. I filed, they didn't show, I won, sent a court order to the bank to collect from their checking account, payday came and I wiped out their account as soon as they deposited their paycheck."
 
Back
Top