I apologize in advance but this will be a long story. At the end of last year a few things happened - my age old mechanic closed his shop before winterizing time and I knew I was on my way to needing a carburetor rebuild. My boat is old but very dear to me and somewhat fanaticaly maintained and touched by very few hands. It is a 1991 Chaparral 2000SL with a VP DP 570 and it scoots. I looked around for a somewhat reputable place to winterize - thinking to some degree - how hard can this be? I had it done. Fast forward to about a five weeks ago. I went to start the preseason prep routine with my son - the oil change. We found a screw driver in the bilge - not one of mine. Figured the winterizing crew got careless but did not think much more of it. The next week we put the boat in the water - fought with it with a stubborn (not working) choke to get it started. It sounded really weird and different than ever. I got it out of the 'no-wake' zone and hammered it thinking I needed to get the cobwebs out of it. It would not even plane. I went less than 100 yards and decided it was time for the carb rebuild but I could not get over this sound. I opened the hatch and looked inside the engine compartment. The winterizing gurus not only left a screwdriver in the bilge, they left a hose disconnected that was supposed to connect to the exhaust manifold on the port side. The stainless steel clamp was nowhere to be found so I bought one and reinstalled the hose. I removed the carburetor and had it rebuilt (by known experts (Carburetor Specialists in Alpharetta, GA - Awesome guys!!!). I reinstalled it. I put in the water today. Started right up. Could tell it wanted to run. Started running hot while at the dock. I pulled it back out. I checked the impeller. It is perfect (just replaced it last year). Obviously no water is getting to the impeller or air is getting sucked in from somewhere and there is a weird sound. Engine is definitely running dry. How do I get it primed. This has NEVER happened before!! I can only figure it HAS to be something resulting from the winterization. I absolutely do not want those guys touching my boat again. I appreciate the help in advance and again - sorry for the long post.
Can't suck winterizing....impeller good.
- Thread starter sbbamafan
- Start date
- Joined
- Jan 1, 2000
- RO Number
- 2006
- Messages
- 359
Double check the flow of the raw water. I've heard that on older VP stern drives that the inlet and outlet hoses on the raw water pump can be installed incorrectly causing overheating. Check the flow out of the raw water pump after the correct connections are confirmed. Should fill a 5 gal bucket quickly.
- Joined
- Jan 1, 2000
- RO Number
- 2006
- Messages
- 359
Additionally if you unit has the butterfly valves in the exhaust runners, one is most likely melted to the shaft and stuck in an almost closed position.
This is a Fresh Water Cooled only engine yes?
If your RW pump looks like this Sherwood P105 with inlet and outlet on the same side, as Michael said above it can be easy to have the supply hose going to the outlet instead of inlet, and vice versa if you don't mark those barbs with arrows or In/Out.
https://marinepumpdirect.com/sherwo...MI0_OCzqjQ6QIViZWzCh11FQrlEAQYASABEgL4uPD_BwE
Also , you can install a brand new perfect impeller and if the housing wear surface is at all scored it will not generate enough suction to lift sea water to the pump at low rpm . But it could do that at higher rpm when the pump acts as a centrifugal pump and the vane tips don't even touch those wear surfaces. So ...if... it is hot at idle but cools at higher rpm that is a strong clue the pump needs replacing or rebuilding if that is reasonable.
If, in fact, your RW was not pumping , that new impeller is likely melted and needs checking now at the very least.
The "butterfly valves" are exhaust shutters or flappers and the exhaust hose has to be removed from the risers to access them inside the hose. As Michael noted, overheat caused by lack of water flow can quickly melt fuse the shutters to the hose and severely restrict the exhaust and induce engine back pressure. When that happens , one can hear a much different back-pressure exhaust note somewhat similar to someone trying to talk with a hand or cloth over their mouth. Back-pressure affects water flow as well as exhaust flow from the cylinders.
Here's one type of flapper, not sure what yours are like:
https://bpi.ebasicpower.com/shop/vo...th-internal-flapper-aq-876633-9-850004-875828
The shutters were there to help keep seawater from flowing back to the engine , but years ago VP released a bulletin advising to leave the shutters out as they were causing more trouble than they were preventing, as long as specific riser heights above the waterline were incorporated.
You could have a restriction at the engine's main RW water intake, or the risers could be clogged or have other flow restriction.
I'd probably try running a hose from the RW pump outlet into a bucket and start the cold engine to see if you get any flow. If not , will it flow at very brief higher rpm ?( Don't run it at high rpm in N.)
FWIW -The spec ...minimum... RW flow rate for my Crusader FWC 5.7L engines is 5 gallons in 15 seconds at 4000 rpm. I don't know anyone who would try that at 4000 rpm but it does mean there should be substantial flow even at much lower rpm.
If your RW pump looks like this Sherwood P105 with inlet and outlet on the same side, as Michael said above it can be easy to have the supply hose going to the outlet instead of inlet, and vice versa if you don't mark those barbs with arrows or In/Out.
https://marinepumpdirect.com/sherwo...MI0_OCzqjQ6QIViZWzCh11FQrlEAQYASABEgL4uPD_BwE
Also , you can install a brand new perfect impeller and if the housing wear surface is at all scored it will not generate enough suction to lift sea water to the pump at low rpm . But it could do that at higher rpm when the pump acts as a centrifugal pump and the vane tips don't even touch those wear surfaces. So ...if... it is hot at idle but cools at higher rpm that is a strong clue the pump needs replacing or rebuilding if that is reasonable.
If, in fact, your RW was not pumping , that new impeller is likely melted and needs checking now at the very least.
The "butterfly valves" are exhaust shutters or flappers and the exhaust hose has to be removed from the risers to access them inside the hose. As Michael noted, overheat caused by lack of water flow can quickly melt fuse the shutters to the hose and severely restrict the exhaust and induce engine back pressure. When that happens , one can hear a much different back-pressure exhaust note somewhat similar to someone trying to talk with a hand or cloth over their mouth. Back-pressure affects water flow as well as exhaust flow from the cylinders.
Here's one type of flapper, not sure what yours are like:
https://bpi.ebasicpower.com/shop/vo...th-internal-flapper-aq-876633-9-850004-875828
The shutters were there to help keep seawater from flowing back to the engine , but years ago VP released a bulletin advising to leave the shutters out as they were causing more trouble than they were preventing, as long as specific riser heights above the waterline were incorporated.
You could have a restriction at the engine's main RW water intake, or the risers could be clogged or have other flow restriction.
I'd probably try running a hose from the RW pump outlet into a bucket and start the cold engine to see if you get any flow. If not , will it flow at very brief higher rpm ?( Don't run it at high rpm in N.)
FWIW -The spec ...minimum... RW flow rate for my Crusader FWC 5.7L engines is 5 gallons in 15 seconds at 4000 rpm. I don't know anyone who would try that at 4000 rpm but it does mean there should be substantial flow even at much lower rpm.
Sandy-
Thanks for the reply - much help. It is raw water cooled. I did look at the impeller. It is less than a year old and perfect. Your thought that maybe the guys that winterized swapped hoses on the pump is a possibility - incredibly stupid but a possibility. The boat is about thrity miles away so I will definitely check later this week.
As for bellows, that is a very big job isn't it?
I also ordered a new thermostat today - just in case. Could it be a thermostat??? I thought about it last night.
As for a restriction on the intake side, my logic keeps taking me back to the fact that this was NEVER a problem until they winterized and there were other careless issues with the winterizing. Again, those two hoses are easy to check. From looking at a sketch I found online, the upper one goes to the thermostat housing and the lower one the hose that runs along the block - I guess to the outdrive sourcing the water. Correct?
Thanks for the reply - much help. It is raw water cooled. I did look at the impeller. It is less than a year old and perfect. Your thought that maybe the guys that winterized swapped hoses on the pump is a possibility - incredibly stupid but a possibility. The boat is about thrity miles away so I will definitely check later this week.
As for bellows, that is a very big job isn't it?
I also ordered a new thermostat today - just in case. Could it be a thermostat??? I thought about it last night.
As for a restriction on the intake side, my logic keeps taking me back to the fact that this was NEVER a problem until they winterized and there were other careless issues with the winterizing. Again, those two hoses are easy to check. From looking at a sketch I found online, the upper one goes to the thermostat housing and the lower one the hose that runs along the block - I guess to the outdrive sourcing the water. Correct?
I went back to the boat last night and found the problem. The 'winterizers' left another hose disconnected. Fortunately I found it quickly. I am really not even certain they needed to disconnect this particular hose. It is the hose that leads from the impeller/pump to the transom - at the transom area. It was easy to see - not so easy to reconnect around the manifolds, steering linkage, etc. but I got it done. I guess it was more difficult for me since I had shoulder surgery 13 weeks ago. It would seem that hose would have drained fine from the once the impeller end was loose - but I dont claim to be an expert. I would say the people that did it were not either.
Now I am just concerned over any potential damage or long term damage. I know the rubber exhaust hose has some internal damage from the heat. How can I tell if these are just a 'little' burned versus DAMAGED short of removing them and replacing them. I know replacing them is a pain and requires removal of the manifolds. I also will do a compression check to make sure there is no engine damage from the heat. Is there anything else I can/should do? I checked impeller and it is fine. I keep a spare just in case.
Now I am just concerned over any potential damage or long term damage. I know the rubber exhaust hose has some internal damage from the heat. How can I tell if these are just a 'little' burned versus DAMAGED short of removing them and replacing them. I know replacing them is a pain and requires removal of the manifolds. I also will do a compression check to make sure there is no engine damage from the heat. Is there anything else I can/should do? I checked impeller and it is fine. I keep a spare just in case.