Alpha1 350 raw cooled boils and ticks rapidly after short time on muffs

[Johnlink]

Hi all - my 1st post. Have a 1986 alpha1 5.7L which has recently had a new impeller (mechanic fittted) and a new thermostat (me fitted). During the thermostat fitting I discovered that the upper cooling hoses were wrongly connected so rectified IE t-stat cover outlets to bottom of manifolds, and foward T style outlet hoses to the risers (have had dry joint manifolds fitted x mechanic recently as well). Anyway as I drained a lot of the sitting water out of my system during the hose work I guess the water in the block and manifolds was pretty dry. Anyway upon starting up on the muffs (garden hose full bore has been OK in the past for flow) the engine temp gauge quickly got up to around 200deg F so quickly shut down - then heard a loud rapid ticking sound and boiling sounds, manifolds and risers too hot to rest hand on, but both seemed to be about the same temp. My next idea is to try with the leg in a large drum of water. Could my problem be low flow from muffs not filling out engine internal passages so some sort of air lock? The hoses to the manifolds and risers seem to be hot to touch as well so probably flowing out of t-stat housing. I am also thinking of getting some clear hoses to fit in-line to double check for flow? Possibly also connect hose directly to circulation pump on front of engine and check the flow out of the leg feed hose to see if impeller doing OK. Very low on funds so have to try to self solve to avoid stiff mechanic bills!

 

[Lou C]

Don’t run it in a drum you need pressurized water from the hose to get the impeller to prime. I would:
1) get the better quality round Mercruiser muffs with the metal rod clamp these use softer rubber that better conforms to the lower unit. I have found that cheaper aftermarket ones use stiff rubber that leaks too much water.
2) fill the engine and manifolds with water before starting

 

[Scott Danforth]

only way a drum of water works is if you can get the whole outdrive in the drum. that makes the drum big enough to float the whole boat in it

you have a blockage somewhere. or you replumbed wrong

 

[Drcoffee]

Were the hoses rerouted when the dry joint risers were installed? It wasnt overheating before you swapped hoses?
disconnect the fresh water supply, crank the engine and see if the impeller is working.

 

[Lou C]

The thing with these warm manifold systems which looks like what you have; the elbows should be fed by a constant supply of cool water but the manifolds don’t get water flow till the thermostat opens. This is to prevent condensation in the manifolds by keeping the manifolds hotter than 120*F. Make sure the hoses are routed correctly, and the thermostat opens fully.

 

[76SeaRay]

Does your new thermostat have a small air bypass hole so that the block can fill fully and during filling let the air bleed past the thermostat with it closed?

 

[crazy charlie]

The hose coming from the power steering cooler to the stat housing should be cool.Pull that hose and check the water flow while running on muffs.Checking the impeller flow is where I would start and making sure you didnt install the tstat upside down would be my next check.Then confirm the hoses that you said were backwards.Charlie

 

[Johnlink]

Hi All - thanks for all the helpful replies. Yesterday I disconnected the leg raw water supply hose and cranked the motor - impeller pump was going well.

Next I ran the garden hose in to the same hose and filled the block till water ran out the inspection plugs at the top of the elbows.

Then started on muffs but still the same problem - rapidly heated up to about 210degF.

BTW I fitted the T-Stat correct way up it is a 140decF unit supplied by local Merc Dealer he made sure it was correct for my engine 1986 model / serial # (old T-Stat had frozen partly open see pic).

So assuming all is good up to engine pump inlet I am thinking; cracked or corroded pump rotor, dud T-Stat (did not boil test before fitting), blockages in manifolds/elbows (both relatively new). I am seeing usual amount of hot water exiting the leg outlet and exhaust when running on muffs.

 

[Johnlink]

Sorry the video does not seem to load on to this site - it was just a shot of the water gushing out of the leg/impeller feed during cranking. Pretty sure the leg water feed is OK esp since mechanic fitted replacement about a month ago.
Below is recent history of the engine re running temps all taken after about 20Klm sea run (apart from last pic which is on trailer on muffs after approx 5 mins @ 1500rpm.)

 

[Drcoffee]

Might be time to pull the circulating water pump. A new pump is about $100 and easy to install DIY

 

[crazy charlie]

I would pull the tstat and run w/o and see what that does to the temp.Also make sure the Tballs are moving freely.Next I would switch the hoese back to the way they were when you determined they were incorrect.Always possible YOU were incorrect.Been there...done that!! Circulator is always a good idea however it will usually spit some water out prior to failing.They are designed to do that.Charlie

 

[Johnlink]

REPORTING BACK.
OK guys great suggestions thanks to all for your thoughts - today I changed the cooling hoses back to the way they were originally AND ENGINE RAN COOLER. Of course the hoses no longer send hot water to the manifold lower inlets, and the cool water is going up to the elbows. So the boat no longer runs a WARM MANIFOLD system so do I new get reduced manifold life via lower temps and condensation? If this is now the "correct" hose connection when using dry joints have Mercury dropped the warm manifold theory? Mechanic mentioned that my older style 6 bib outlet tstat housing water flow may differ from newer models with dry joints standard?

OBSERVATIONS
1. Engine ran at 185deg F on gauge (20deg cooler) jerked around a lot like the tstat was working, but it is rated at 140!
2. Cooling hose tstat housing to lower manifold inlets was quite cool and hose from tstat top outlets was very hot
3. Noticed hot water coming out of transom shield PORT side outlet like a kids water spurting gun but nothing out the STARBRD side (also a bit of a rust flake half blocking the PORT outlet hence the strong squirting about half a metre)
4. Could just lay my hands on the manifolds and elbows for about 1/2 second each
5. Still a minor amount of boiling and ticking noises after shut down

Tomorrow I may pull the main circulation pump though it has shown no signs of leaking or bearing noise. Or is it possible that my tsat housing with the 6 bib outlets is not compat with the dry joint manifolds? They did work OK at first with temp gauge showing 150deg F on long sea runs. Another likely culprit could be rust scaling slowing down the whole cooling flow? Don't really want to pull the manifolds unless all else fails. BTW I do not have any T-Balls on my tstat cover outlets?

 

[Lou C]

OMCs and Volvos always had a cold manifold design and I don’t think that the manifold life was any different. The ones on my engine are exactly the same as what Volvo used from about 1994 all the way to the cat converter era. They do run cool; 90-100*F at idle the hottest they ever get is about 135-140 after coming off plane, and quickly cool down after that. I think OMC and Volvo used a 160 stat to reduce condensation with the cold manifolds set up. I don’t have this info from documentation but just a guess on my part. I did try a 140 stat because I’m in salt water and the 140 is supposed to be better in the salt but when I checked the manifolds after running at idle there was some condensation. So I went back to the 160 stats I have always used.

 

[Drcoffee]

drill a 1/8” hole in the t-stat flange. This will let air escape and reduce air pockets. There is no downside to doing this.post pics

 

[crazy charlie]

"QUOTE drill a 1/8” hole in the t-stat flange. This will let air escape and reduce air pockets. There is no downside to doing this.post picsdrill a 1/8” hole in the t-stat flange. This will let air escape and reduce air pockets. There is no downside to doing this.post pics END QUOTE" I dont know where this advise is coming from but DONT DRILL ANYTHING!! Hang in there and be patient,we will help you figure this out.The motor is back to running at more normal temp so progress!! charlie

 

[tank1949]

Sorry the video does not seem to load on to this site - it was just a shot of the water gushing out of the leg/impeller feed during cranking. Pretty sure the leg water feed is OK esp since mechanic fitted replacement about a month ago.
Below is recent history of the engine re running temps all taken after about 20Klm sea run (apart from last pic which is on trailer on muffs after approx 5 mins @ 1500rpm.)

were riser gaskets open or closed? Motor's photo indicates that you have a sea water cooled motor and no heat exchanger.

 

[Johnlink]

Hi Tank1949 - I have restricted gaskets on my elbows, the restricted hole is just under the cooling water supply hose IE to the front of boat side. Yes I have sea water cooled system and no heat exchanger.
My current theory on the overheating is that it may be rust scaling and restricted flows through the elbows. When I screwed out the inspection plug at top of the PORT elbow it bound up after a couple of turns and then came out quite reluctantly - had rusting and scale deposits on inside surfaces and actually partially stripped out the thread during removal. Thinking back to the start of my overheat problems I found that the PORT elbow was much hotter to touch as well. Anyway there is a bit of a story to my elbows ...

ELBOW HISTORY
6 years ago got rid of original manifolds and elbows old style wet joint
Merc dealer fitted genuine dry joint units - cost a lot
After the job my engine hatch would not close due to height of elbows
Dealer was not interested to remedy problem
Next found a mechanic who had a set of unused genuine Merc lower height elbows
He fitted these for me as a clean swap just labor costs
Yesterday I took a closer look at those elbows and found they were not genuine Merc, they were BARR brand! (does this stand for Bloody Awful Reject Rubbish)
So for it may make more sense if they are rust scaling earlier than the manifolds?
Tomorrow I plan to pull off the BARR's for a check - hopefully I can clean if just deposits blocking around flow holes?

 

[Lou C]

Actually Barr is better than the other aftermarket stuff that is what most mechanics think here at least.Yes they can be rodded out to clear the corrosion. Keep in mind elbows always corrode faster than the manifolds do because manifolds have water in them all the time while the water passages at the top of the elbow drain after you shut off the engine and are exposed to salt air and corrode faster. In face some people in salt water regions change elbows twice as often as manifolds for this reason.
I installed a complete one piece to two piece conversion on my OMC V6 using Barr manifolds & elbows and Volvo 90* exhaust down pipes and hoses to replace the old NLA OMC one piece V6 manifolds. No problems with leaks or overheated exhaust and they’ve been on for 4 years. All cast iron exhaust parts will rust internally unless they are coated which I think some of the Merc ones might be. When you had the original wet joint system on did you have any problems with hot running? Also the Merc dry joint gasket used with raw water cooling has to be installed a certain way with respect to the restrictor hole, but it seems like you have that right. Ultimately you could always get a set of Merc correct height elbows for your application.

 

[tank1949]

Hi Tank1949 - I have restricted gaskets on my elbows, the restricted hole is just under the cooling water supply hose IE to the front of boat side. Yes I have sea water cooled system and no heat exchanger.
My current theory on the overheating is that it may be rust scaling and restricted flows through the elbows. When I screwed out the inspection plug at top of the PORT elbow it bound up after a couple of turns and then came out quite reluctantly - had rusting and scale deposits on inside surfaces and actually partially stripped out the thread during removal. Thinking back to the start of my overheat problems I found that the PORT elbow was much hotter to touch as well. Anyway there is a bit of a story to my elbows ...

ELBOW HISTORY
6 years ago got rid of original manifolds and elbows old style wet joint
Merc dealer fitted genuine dry joint units - cost a lot
After the job my engine hatch would not close due to height of elbows
Dealer was not interested to remedy problem
Next found a mechanic who had a set of unused genuine Merc lower height elbows
He fitted these for me as a clean swap just labor costs
Yesterday I took a closer look at those elbows and found they were not genuine Merc, they were BARR brand! (does this stand for Bloody Awful Reject Rubbish)
So for it may make more sense if they are rust scaling earlier than the manifolds?
Tomorrow I plan to pull off the BARR's for a check - hopefully I can clean if just deposits blocking around flow holes?

In NW Florida, most use open gaskets, since the water (Gulf, River, Bayous ) stay warm compared to other parts of the county, if they have an open cooled system. I don't know of anyone who uses restrictor gaskets, but I live on the Gulf Coast. I got away from open cooled systems. It will be a task, but I'd pull risers and hoses and start testing water flow. You may have to pull circulating pump and PS heat exchanger. Follow the water from transom hose through risers. Good luck.

 

[Rick Stephens]

Sounds to me as there is no exit for the water going to the manifolds now that the gaskets are closed off...