VST question for 5.7L TBI....

[fmt2bx]

Hi,
I got this motor transplanted to our boat. It has a fresh water cooling system. Towards the rear of motor is the VST. Out of the VST is a small barb which, if I am not mistaken, should be connected to the thermostat housing. the motor came with no connection to the barb.
Could someone tell me where should the tube from this barb should be connected to when using a fresh water cooling system? Is there suppose to be some kind of check valve to prevent water from going to VST?
Here are some pictures... (There is a small hose connected to barb right now with a small yellow cap at the end)

Thank you.

 

[alldodge]

Your Frankenstein motor keeps having things show up. In you previous the ECM number came up as a Gi, but being a TBI and VST would mean its not a Gi, because the Gi is MPI

The VSY tank had a line which would go from the top of the tank to the flame arrestor. It was positioned there so if the tank started flooding, all excess fuel would dump into the intake

 

[fmt2bx]

Your Frankenstein motor keeps having things show up. In you previous the ECM number came up as a Gi, but being a TBI and VST would mean its not a Gi, because the Gi is MPI

The VSY tank had a line which would go from the top of the tank to the flame arrestor. It was positioned there so if the tank started flooding, all excess fuel would dump into the intake

Thanks Alldodge.... Yeah this motor is tough to figure out, lots of parts not belonging there...

 

[cobalt1999]

Look under the starboard side of the throttle body assembly, there should be a device called an impulse limiter part # 3852225 screwed into the side of the intake manifold with a 45 degree elbow. This is where Volvo Penta connects the vapor hose from the barb fitting on the VST.
Make sure you have sea water flowing thru the VST tank (the fitting on each end of the tank by the bottom). If there is no cooling, the high pressure pump would overheat.

 

[fmt2bx]

Look under the starboard side of the throttle body assembly, there should be a device called an impulse limiter part # 3852225 screwed into the side of the intake manifold with a 45 degree elbow. This is where Volvo Penta connects the vapor hose from the barb fitting on the VST.
Make sure you have sea water flowing thru the VST tank (the fitting on each end of the tank by the bottom). If there is no cooling, the high pressure pump would overheat.

Hey Cobalt1999! Thank you very much, I will look tomorrow for the impulse limiter. A quick search on the web to see what I am looking for showed something like that.... Right?



Also, just to be clear, There is a hose on top of VST already connected to the base of the Throttle body (A) in the picture... I am looking to connect (B). I ran the motor a few times on the trailer and in the water. About 20 min max. There was water dripping off (B), it wasn't fuel for sure. Could have been that this motor has been sitting for over 5 years or so and water got in there. I didn't want to run it longer, afraid I could damage something...

Thank you for the recommendation() about the water, There is sea water flowing throughout the system.

Here is the pic. I will look again tomorrow to see if I can locate that impulse limiter.

Thanks again..

 

[cobalt1999]

Yes, That is the fitting you are looking for..
Yes, That is what hose A should be connected too.
Hose B is most likely the cooling line coming off the starboard side of the VST tank, there is another line coming off the tank on the port side and should be going to the port elbow. That is why I said water has to flow thru the tank. (Make sure you blow out this line when winterizing or you'll bust the tank)
If your engine was raw water cooled, I believe that hose B went to the top of the thermostat housing.

 

[dypcdiver]

Having just repaired my VST "cobalt1999" is correct. As you no longer have the raw water thermostat housing you will need to find somewhere to tap into the raw water pump supply that feeds to your heat exchanger and run a small diameter 3/8" ID line to the barb (No.17) that has the yellow plug in it.
The discharge goes to the port riser. ( No. 47.)

 

[fmt2bx]

Yes, That is the fitting you are looking for..
Yes, That is what hose A should be connected too.
Hose B is most likely the cooling line coming off the starboard side of the VST tank, there is another line coming off the tank on the port side and should be going to the port elbow. That is why I said water has to flow thru the tank. (Make sure you blow out this line when winterizing or you'll bust the tank)
If your engine was raw water cooled, I believe that hose B went to the top of the thermostat housing.

Cobalt99!
Thank you for your quick reply. I really appreciate your help and I apologize for being so ignorant about this water cooler subject.
I have had some time this am and here is what I have. Not saying this is how it should be , no idea what the previous owner might have done with the motor...
From the picture, The raw water coming from stern drive impeller goes to the power steering cooler, from there it enters the fuel cooler port side then comes out in the back of the fuel cooler. from there it goes the raw water pump .




Hoses disconnected...




I have tried to see if I could blow or suck air (very gently) on the mysterious B barb. I can't do either. Once again not sure what to make of this... I definitely get water going through the fuel cooler.

Now, on the intake manifold I found this cap. Could it be that the B barb is a safety vent, if fuel cooler leaks or over flow inside the fuel is re-routed to intake manifold, as Alldodge suggested?

Thanks again..

Fred

 

[fmt2bx]

Having just repaired my VST "cobalt1999" is correct. As you no longer have the raw water thermostat housing you will need to find somewhere to tap into the raw water pump supply that feeds to your heat exchanger and run a small diameter 3/8" ID line to the barb (No.17) that has the yellow plug in it.
The discharge goes to the port riser. ( No. 47.)

View attachment 327094

Thanks dypCdiver!! If you have a chance, could you look at my reply to Cobalt99 (previous post). Is your fuel cooler connected like this?
Thanks

 

[fmt2bx]

Disregard my last 2 post.. Got the VST out and here is the issue..... Totslly clogged up...Now going to try to take this apart and see what i can do... Are you aware of any videos or post about taking this apart?
Thanks

 

[fmt2bx]

GOT IT!!!!!

I wanted to post the following in case it might help someone down the road...
This type of VST has been discontinued by Volvo, I imagine there might be some work around it but if the VST is plugged up , this might be a way the avoid very $$$ substitute.


I got the VST out, it was clear that there was a lot of deposit inside the tank preventing it from working properly. I couldn't get any water coming out of starboard side ..



Inspected with boroscope .....
















Now on this last hole there was something which looked a bit different, I poked gently with a small phillips screw driver and got to reveal a hole which had been completely clogged up, preventing the water to flow inside the reservoir off to the barb on the starboard side!!!!





In order to clean all the deposits as well as possible I used vinegar and gave it a 1 hour sit...




I then rinsed it with hot water and that cleared up most of the stuff..

I rigged a plug for the port side and use hot water to flow from rear side inlet to tank out the starboard side outlet...Did that for about 20 min... Now it is as clean as I can get it.


It all makes a lot more sense now that I took the VST off and was able to play with it...

Now a bit more cleaning, some sanding around the barbs and some painting to protect it the best I can....

I posted a small video here as well..

Thank you very much for all your help...

Fred

 

[dypcdiver]

Interesting, I have the 5.0Gi which is plumbed slightly differently, as in the diagram I attached.
My VST was also completely blocked at both the inlet & discharge. Mine had corroded though from the water side to the fuel side and required a new body, which at first seemed to be unavailable. However I tracked one down in Sweden. All is well now.

 

[alldodge]

Why not just take it apart?

 

[fmt2bx]

Interesting, I have the 5.0Gi which is plumbed slightly differently, as in the diagram I attached.
My VST was also completely blocked at both the inlet & discharge. Mine had corroded though from the water side to the fuel side and required a new body, which at first seemed to be unavailable. However I tracked one down in Sweden. All is well now.

Glad you could find a new one!
Thanks DypCdiver for your help.

 

[fmt2bx]

Why not just take it apart?

I couldn’t get the top off. I was afraid to damage something and this part being unavailable, that would have been too costly .

All dodge, thanks for your help too.