View Full Version : Chevy 350


mikealston2428
05-25-2012, 09:13 PM
Hi All,

I have a question.

I have a chevy 350 inboard with a Mercruiser stern leg.

The motor has a header tank (I think this is what it is called) with a heat exchanger.

What I want to know is, can I run the motor with out the leg in the water or connected to a water hose.





If I don't put the leg in gear (leave in in neutral) and only run it for a short time so the water running thru the motor doesn't start getting to hot.

The reason I ask this is because I would like to be able to give the motor a quick warm up at home on the trailer before heading for the boat ramp.

Cheers,
Mike.

IMP-ish
05-25-2012, 10:46 PM
Alpha drive? Get a "pair" of outdrive muffs for $15 that you hook a hose to. If you run the engine with the outdrive dry you run the risk of damaging the impeller in the outdrive. It won't be lubricated by the water but will still be spinning. It can be damaged in a couple minutes so it won't pump as well.

Frosty
05-26-2012, 03:59 AM
And --dont run it with the leg fully up. Must put the leg down.

CDK
05-26-2012, 05:18 AM
Yes, you can run the engine with the drive down and in neutral for a short time.

To define "short time": if there is a smell of burning rubber, that means the exhaust hoses are smouldering because they don't get water from the discharge ports behind the risers.
The header tank and heat exchanger are there to prevent internal engine corrosion and allow a more efficient operating temperature. They are not there to facilitate dry running.

PAR
05-26-2012, 06:06 AM
The drive leg's impeller will self destruct in very short order without water. I change plenty of them, because owners think they have something magical in their outdrives.

midnitmike
05-26-2012, 12:10 PM
Mike,
I suppose I can understand the desire to warm up the engine prior to making your trip to the boat ramp, but what I can't quite grasp is why you would consider doing this without taking even the simplest precautions. You've gotten the best possible advice already, so I won't add anything to the list. I'm just curious as to why you think this is a viable option?

MM

Frosty
05-26-2012, 12:18 PM
Yes, you can run the engine with the drive down and in neutral for a short time.

To define "short time": if there is a smell of burning rubber, that means the exhaust hoses are smouldering because they don't get water from the discharge ports behind the risers.
The header tank and heat exchanger are there to prevent internal engine corrosion and allow a more efficient operating temperature. They are not there to facilitate dry running.


What are you saying? this is incorrect advice, the rubber impellor pump is in the leg above the gearbox that turns with the engine.

Nothing to do with exhaust rubbers.

mydauphin
05-26-2012, 02:57 PM
You can't warm up engine without water without frying it. It is that simple enough.

Some parts will get warm, some hot and some will melt. And you will only know which when you rebuild engine if that is even possible.

mikealston2428
05-26-2012, 08:28 PM
Thanks guys,

Seems most of you are off the opinion this was a silly question.
I was 99% sure I should definitely not do it.

I will give you abit of back ground as to why I asked.

I as many boat owners don't have the space at home to store my boat so have been lucky enough to find a great mate with space and willing to let me store my boat at his house.

When I have not used the boat for a couple of weeks I have to take the top off the carburettor and pour a small amount of petrol in the get it started and then warmed up, this understandably get others waiting for me to get off the ramp upset.

I have a pair of earmuffs that I warm the motor up at my mates place before heading off.

When I am having a early morning start I cant fire the motor up at my mates place and wake everyone up at 4:00 in the morning as you could imagine that would not go down to well.

I guess I will have to put up with the abuse at the ramp, I don't like upsetting fellow boaties but don't really have a choice.

Thanks for the advice.

Mike.

Frosty
05-26-2012, 10:34 PM
It should have an accelorator pump. Pump the throttle a few time maybe up to 10 to squirt fuel in.

These big ******* need a lot of fuel to fire up.

IMP-ish
05-26-2012, 11:03 PM
Any friends who are mechanics? Bet you can get it to start up easier without having to pour gas in. Never had to do that on any of my boats.
Should turn over in a few seconds once you get the hang of feathering it right. My 350s started as easy as any of my engines. Warm up for 1-2 minutes is all it takes to idle smooth. Adjusting the carb some people have it and some people can't get it right. I'm not great at spotting carb problems, got a friend with the touch and he cleaned up and adjusted my carbs in an hour better than I had ever got them.

Also want to add one bit - once had a guy helping me and he started both engines before I noticed no water. Ran for 30 seconds to a minute dry. Didn't kill the impellers. Once in a while you luck out and they are fine. Was launching, and went ahead and it ran the whole season with no temp problems. Now, DON'T do it because chances are good you will hurt them. Only added that because once in a while you luck out.

midnitmike
05-26-2012, 11:04 PM
Hi Mike,
OK that explains the situation a bit better. Can we assume that you've already tried Frosty's advice about pumping the throttle a few times, it still wouldn't start, and so now you're forced into dumping gas down the carb? If so you might want to check out that same accelerator pump to see if it's functioning properly. It could be the choke is stuck open, so the only way it will start when it's cold is with a over rich fuel air mixture.

Whatever the cause it sounds like a few minutes of troubleshooting this malfunction is in order.

MM

Frosty
05-26-2012, 11:06 PM
Also want to add one bit - once had a guy helping me and he started both engines before I noticed no water. Ran for 30 seconds to a minute dry. Didn't kill the impellers.

But they were submerged and lubricated by water, not pumping is another issue.

IMP-ish
05-26-2012, 11:21 PM
No, it was in the storage building 500' from the water. Didn't have spare impellers. I went ahead with launching anyway. Ran all day and all season with no temperature problems. It did have green antifreeze in the rest of the system from being winterized, but the water pumps in the drives would have been dry or dry within a second with no muffs on them, I think. I lucked out that time.

mikealston2428
05-26-2012, 11:25 PM
I have tried pumping the choke a heap of times but no fuel skirts in to the carb, sounds like i need to have this looked at.

On a different note the last trip out the motor run terrible, it was blowing real black smoke and there was black sot floating on the water behind the boat from the exhaust, never done this before.

The engine seemed really choked up, took awhile for engine to clear it self and rev high again, not sure if the timing has gone out and or the carb needs adjusting.

Real frustrating as up until now it as run great.

Mike

Frosty
05-26-2012, 11:25 PM
Your post said you noticed no water why would there be 500' from the waters side.

IMP-ish
05-26-2012, 11:29 PM
Hose from spigot.

Frosty
05-27-2012, 01:03 AM
Hose from spigot.


Then the impellor was lubricated by the water.

IMP-ish
05-27-2012, 01:14 AM
Having a spigot on the wall doesn't make the water flow to the outdrive by itself!
No water.
I've done other stupid things.
I once put a boat in with no drain plug. Yea, the age old marina "did you check the drain plug" and I still forgot it once. This one I lucked out. Also lucked out when I left the drain plug out but that's another story.

Frosty
05-27-2012, 01:17 AM
Don't run an engine out of the water or without supply it says so on page one.

Carteret
05-27-2012, 08:53 AM
I had one one time that was hard to start due to fuel siphoning back to the tank. The ramp angle actually aggravated the problem. I installed a check valve in the fuel line and the check cured the problem

Frosty
05-27-2012, 09:48 AM
I had one one time that was hard to start due to fuel siphoning back to the tank. The ramp angle actually aggravated the problem. I installed a check valve in the fuel line and the check cured the problem

Then your fuel pump was the problem. The pump itself has 2 valves.

No system can siphon back the fuel in the float chamber, and there should always be enough there for the accelerator pump unless the vehicle / boat had been left a looong time.

The Accel pump takes fuel from the bottom of the bowl so there should always be fuel to pump and keep it going until even a bad pump and dry pipe could catch up.

midnitmike
05-27-2012, 02:31 PM
I have tried pumping the choke a heap of times but no fuel skirts in to the carb, sounds like i need to have this looked at.

On a different note the last trip out the motor run terrible, it was blowing real black smoke and there was black sot floating on the water behind the boat from the exhaust, never done this before.

The engine seemed really choked up, took awhile for engine to clear it self and rev high again, not sure if the timing has gone out and or the carb needs adjusting.

Real frustrating as up until now it as run great.

Mike

Hi Mike,
The 32' Uniflite I have in the yard has two of these 350 chevy's in it, so I can empathize with you. Although I picked the boat up for the salvage cost after it sunk last Winter I did have the "pleasure" of being aboard her on a number of sailings with the previous owner over the last few summers. Other then the normal unreliability that you get with gas engines I have to admit that they had more then their fair share of carbs problems thanks to the installed Quadra Jets.

First let me say that pumping the "Choke" won't induce gas flow into the carb...all you're doing is opening and closing the choke plate. If the engine is cold and off the choke should be closed...you'll have to manually open the choke to see into the carb throttle body. With the choke open either have a friend operate the throttle control or disconnect it from the carb and do it yourself. With each movement of the throttle you should see gas being squirted into the engine intake manifold. You don't have to do this more then once or twice to know if your accelerator pump is working. If it is then you can move on because that's not your problem.

In your previous post you mentioned that the engine was hard to start and required fuel being poured into the intake, now you're reporting lots of black smoke and soot as well as poor performance. Both are indicitive of a malfunctioning choke. In one instance it's stuck open and requires lots of fuel to get started, and the next it's probably stuck closed causing all that black smoke. In either case I'd recommend you have a mechanic look at it because it's not going to get better over time.

MM

PAR
05-27-2012, 05:17 PM
You are leaking down or suffering from evaporation loses with your hard starting situation. Fuel should remain in the bowel for quite some time (months) without leaking out or evaporating off. This is especially true of marine carbs.

This suggests you have something amiss in your carb or fuel delivery. The issues seems to becoming compound, so take it to someone who knows marine carbs, for a diagnoses.

I suspect you have multiple problems, all minor, but combined causing several issues, such as hard starting, poor performance, poor fuel economy, rough idle, etc. It's likely a simple tune up will cure most of the problems if coupled with a fuel system checkup.

Frosty
05-27-2012, 10:01 PM
The bi metal thermal choke adjustment is critical. 3 screws and you can turn it increasing or decreasing spring effect on the choke flap. It should not be so strong that it wont come off.

A fine point in the middle is whats required. There is a vernier guage marking so you can see what you have done.

tunnels
05-28-2012, 01:43 AM
Stern drive is like a outboard So no leg in the water the pump will die very quickly and yes you have a heat exchanger and a closed system it is possible to run the motor but have to disconnect the drive shaft at the back . Lots a work just fit some ear muffs and be done with it of !! or you could try one of these ok for out boards and also sterndives . DONT PUT IT IN GEAR !!! COLLAPSABLE AND CONNECT THE HOSE AND IT FILLS AND HAS A 3 LEGS THAT ARE JUST TO HOLD THE TOP RING UP THATS ALL :confused:

PAR
05-28-2012, 05:04 AM
Okay Tunnels, I think we've covered the importance of immersed water inlets on the drive leg.

View Full Version : Chevy 350