5.7 prealpha running hot (pics posted) UPDATE!!!!

[v8power]

Hello,

I have a 1980 Cobalt 19cd, 5.7l, 260hp, Pre alpha.

As far as i could tell the drive serial# is, 3343145

The engine serial# is, 5571786

Heres the problem, I installed new center riser manifolds, new risers,
new thermostat housing and thermostat. (140f) And thru hull exhaust.
When engine is at idle, the temp rises up to over 200 degrees.
Water is coming out of both sides of the exhaust. Seems to be less water coming out of the side that the starter is on though. (sorry can never remember starboard from port.) Anyways, when I speed the engine up to around 2000 rpms, the temp comes down to around 140 degrees. But when the temp comes down, the water stops flowing out of the exhaust on the side with the starter. Im thinking Impeller. What do you guys think?

By the way, It was running on muffs with plenty of water pressure.

 

[180shabah]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

How old is the impeller?

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

it was replaced may of last year.

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

i bought the boat in sept, of 09. the impeller was replaced in may of 09, not sure how much use from may to sept.

 

[scutly]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

(sorry can never remember starboard from port.)

left has 4 letters and so does port. i say change the impeller. cant hurt

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

left? Is that looking at the front of the engine. And does anyone know which impeller kit I need?

 

[cr2k]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

standing behind the boat left/PORT (both 4 letter words)
right/Starboard (both longer words)

This totally eliminates "which way were you facing?"

Otherwise all we can tell you is to reset the do-hickey to fix your whatchamacallit.

 

[Bondo]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

left? Is that looking at the front of the engine. And does anyone know which impeller kit I need?

Ayuh,... The Hull's Left is the Portside,... Nothing to do with You....

The Alpha 1,+ Pre-Alphas use the same Impeller kit....
What T-Stat housing did you buy,..?? Does it have the Check-balls in it,..??
If not,... That's your overheat at idle Problem...

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Yes it has the check balls. I bought the tstat housing for converting from log to center riser manifolds. From dennis moore.

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Thanks to all who corrected me on the port and starboard issue.

but does anyone have any idea as to what the problem i am having with the boat?

 

[Bondo]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

but does anyone have any idea as to what the problem i am having with the boat?

Ayuh,... How about a Picture, so We can see how you re-routed the plumbing...
A nice clear 1, posted at 480x640,... No bigger, nor smaller...

 

[Friscoboater]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Those would be GLM manifolds right? Might want to do some research on them. I have heard bad things about the castings and you might have some clogged passages. I would still replace the impeller as they need to be done every year. The fact that it is cooling down when you rev it up means that you have a flow issue.

 

[scutly]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

left? Is that looking at the front of the engine. And does anyone know which impeller kit I need?

i believe from your serial #, that this is your kit impeller kit
lefts and rights pertaining to vehicle parts are determined from sitting in the drivers seat. easy to remember that way

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Well, i pulled the lower unit and the impeller is like new. Housing is like new.
Manifolds dont seem restricted, i can blow air through them with ease. (via my lips). the hoses from the thermostat housing are as follows. the ones that come from the t-fitting with the checkballs go to the risers. the ones from the tstat go to the bottom of the manifolds.

Any other ideas?

thanks for all the help.

 

[Friscoboater]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Stuck tstat?

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

nope. took the housing apart while hot and the tstat was open.

Just checked all water lines with the hose and all seem to be flowing well. ran water through the tube in the upper drive through the power steering cooler, disconnected at the tstat housing and flowed good. ran water through manifold hoses and plugged the riser hoses and water flowed right through manifolds and risers.and discharged great.

Now im really stumped.

 

[SSSuper83]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

You may want to look into the engine water pump...has anything changed on the front of the engine??

Dont want to hijack the thread, but when you changed from the logs to center risers..how did you route the fresh water intake hose to the other side of the engine??

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Circulating pump was fine before the manifold change. Didnt have to reroute the fresh water hose. I bought a tstat housing that has fresh water inlet on the correct side. For log to center riser manifold conversion.

 

[v8power]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Ok. Ive checked everything out.but still, the starboard manifold and riser are getting hotter than the portside. The water discharge seems to be less on the starboard side also. My question here is, if I got a faulty manifold or riser that has a restriction, would it over heat like it is? It gets hot mostly at idle but comes down a bit when i run the engine up to about 2000 rpms.


This thing is driving me nuts.

 

[Don S]

Re: 5.7 prealpha running hot

Re: 5.7 prealpha running hot

Post some pictures of your engine. Include pictures so we can see house routing and type thermostat housing etc.