Specific Cooling Question...CONCLUSION!

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

So i guess everyone is as puzzled as I am about this overheating issue

again;

New impeller
Hoses
140 t-stat
circ pump
risers w/ restrictor gaskets now
Belts

Still overheating gets up to 200 on gauge, but gauge seems to read 5-10 higher then IR temp gauge on temp sender.

A few more pieces to the puzzle that may help diagnose....

I bought an IR temp gauge and here are some of the readings

base of water intake manifold appx 170
circpump inlets and block 175 - 185
exhaust manifolds 210 right at mate to block (same temp on block right at exhaust manifold)
exhaust manifold down to 160-170 3 inches away from block
risers 140-150

more diagnostics done, I took the check balls out, stretched the springs and reset the nylon balls

pulled the feeder hose at the transom and fired it up....water shot straight out, no air, solid stream..this is def not the problem.

No obstructions in power steering cooler either...

Any thoughts would be super helpful!!!

-BAproject

does anyone know the next place to check

 

[crazy charlie]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Had/have same problem in both of my 5.0s.The cure for 1 was replacing the water pocket gasket in the upper drive.It worked on one and slightly improved the other.Still trying to find a way to cure the other.The problem was narrowed to the drive when I put on a spare drive that I bought that just had the water pocket in the upper repalced.Charlie

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Interesting.....where exactly is this gasket.....do I need to remove the entire drive?
Again there is excellent flow shooting through the white poly-pro spout in the transom.....

 

[crazy charlie]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

When you split the drive in 2 parts ,it is in the underside portion of the upper.It houses the tube that recieves the water from the water pump housing.Charlie

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

http://www.iboats.com/Mercruiser-St...ng-Components-Exploded-View/dm/view_id.272967

#41.....right.

If this seal was bad wouldn't my water flow be limited at the transom.

I'm guessing that getting to this is a PITA

BAproject

 

[crazy charlie]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

It would be less.Depends on how bad the gasket is.

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Hello again...

I am still completely boggled as to why my engine is running to hot. I have posted several messages explaining the diagnostics I have run thru to narrow down the problem.

I fear the worst, and that is that there is a blockage in the water jackets of the engine....I have no idea how or if it is even possible to cure this problem. alls orts of crazy thoughs are zipping through my head, like dumping marvel mystery oil into the cooling systems and letting it sit and see if it breaks down anything.....I'm sure this is a bad idea so please chime in and stop me if you concur.

Also, I have correct water flow at the inlet hose on the water dist. manifold....but here's another question....how much water is supposed to be flowing into the large hose that feeds the circulating pump.....

It seems that this is spitting water almost like squirting water from a spray bottle....doesn't seem like adequate flow here....how much water flow should be her????

 

[liquidlew]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Sounds just like the problem I had 2 years ago after new everything, hoses, belts, manifolds, risers, t-stat, t-stat housing, water pumps...and like you I had super flow to the engine, even did the drive in the tub method, and temp still kept going up. My problem was solved when I checked the timing, was at 6 and was supposed to be at 8btdc, set to where it was supposed to be, and badda bing, holding steady at 145! Check your timing.

 

[Howard Sterndrive]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

was the gauge ever verified with a thermometer?
Is 180 overheating?

did you do the 1500 rpm water flow test / bulletin?

those Gen II's had a corrosion issue around the w/p housing. Some needed a good sanding and repainting of the sealing surface. Also, a little bit of stray sealer can block the priming hole.

Also been a couple of recent threads about faulty new impellers.

I'm not convinced there is a problem, but if there is, probably in the lower unit.

 

[liquidlew]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Oops, just missed that last post. You should have big flow at that hose, that should be the one from the power steering oil cooler (if you have one) to the engine circ pump. That's the hose I took off and had super flow. So you could have blockage between the transom and the circ pump?

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

I have checked the outlet on the transom and has excellent flow

I remove the the hose that feeds from the transom to the water distribution manifold....free and clear (back-flushed and reinstalled)

Excellent water flow where this hose comes into water dist manifold....

Bad flow on outlet that takes water to the circulating pump....leads me to believe either water dist manifold or obstruction in the engine itself (this set up mixes hot water from the engine with cool water from the inlet and pushes it to the circ pump)

I had a boat mechanic time the engine for me, I believe he said it was 10 degrees BTDC. I called him again last night to make sure it was indeed timed correctly and he assured me. He is a friend and came to my house to do this ....he's almost as puzzled as me where the problem could be

His recommendation is to remove the exhaust manifolds and either clean them out or replace them.....In my gut I just don't think this is the problem.

Thanks for the advise I do appreciate it!!!

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Hey Howard Sterndrive....

Yes I confirmed that the temp is running high with an IR temp gauge all around the engine. The gauge on the dash is about 10 degrees off, but when I run it hard it reads 200 degrees (so call it 190)...

With a 140 t-stat that is most definitely running hot.

Not sure that it is technically overheating, but its running too hot to be good for the engine, especially because this is a salt water boat. If I could get it to run steady at 165 I would be happy and salt won't crystalize.

 

[liquidlew]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

Hmmm, you sure it's supposed to be 10 BTDC? My Merc manual sez 8, and I have a 1989 4.3, seems to me it should be 8, not 10, you have the same engine/drive I do, still Gen 1. Checking the timing is cake if you have a timing light. I will check my manual again when I go home for lunch today just to be sure. I would tell you to check it out here, but I don't think you can access the manuals here anymore. Bummer.

 

[BAproject]

Re: Specific Cooling Question...HELP PLEASE

Re: Specific Cooling Question...HELP PLEASE

No need to check...the timing is supposed to be 8 degrees BTDC. Mine is currently at 10...now that being said I had to replace the timing chain cover as it had rusted thru.

Believe it or not it is not the easiest thing to find. I ended up getting a chrome plated automotive cover with the detached timing tab ( I know I know some of you will cringe at this). To put you at ease I coated it with 3 coats of epoxy paint.

The tab was not a great fit with the cover for whatever reason and the angle measure may be off by a bit. So it is possible that I am at 8 degrees.

And again, the person who is helping me is a boat mechanic (on the side) and built his cigarette boat from scratch...both engines....blah blah blah....and assured me that I am timed correctly.

I may screw around with it anyways...but still think I dont have enough water feeding from the "t-stat" housing to the circ pump.....any number of issues could create this problem

 

[BAproject]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

Well just did some more diagnostics...and came to a shocking revelation. And I will admit I feel like a moron for not checking this!

My brain has been on overdrive processing this cooling system and what could be wrong....

As posted earlier I replaced hoses...well, the ones on the front...I decide to inspect those pesky little hoses that feed the exhaust manifold (not the risers)

Guess what, both hoses were basically filled with small rusty debris (consistency of sand)....I mean clogged.

So I clean, flushed etc....and re-installed

I have fixed half the problem, the left bank is running at perfect temp (everywhere).....the right bank is running really hot now. This was all checked with one of those IR thing-a-ma-bobs. Circ pump inlets running around 160 both sides...base of t-stat housing at 145.....so all is good in those areas.

Now I have to figure out the right bank....

Any suggestions. Should I just pull the manifold and clean/replace it....seems like there may still be an obstruction in there. Any thoughts? Just seems really strange that this side is getting so much hotter no.....the exhaust riser is getting way to hot as well, around 130...

 

[bruceb58]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

What are the temps of both risers? One riser will always be hotter than the other so that's normal. 130 is not very hot for a riser. In fact, that is pretty cool.

 

[BAproject]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

Hi Bruce,

Yes I have read that one side always gets hotter than the other...but this riser was hot to the touch. I will re-run test tonight to make sure I am giving correct info. That riser actually stayed cooler when the exhaust manifold hose was clogged.....

 

[BAproject]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

to clarify further....

The entire starboard side bank registers 145-150, which is perfect for the 140 t-stat that's in there. The riser is cool on that side runs 95-100 at the top. The only hot spot (180ish) and its maybe 1/4 surface area is right where the exhaust manifold is bolted to the engine, but you move 1/4 away and its right back down to 145-150. The block at at that intersection is 145-150 as well....I assume this is normal.

Now...the port side bank is not even close to this. Everything listed above is 35 to 40 degrees hotter on the port side, block, riser, manifold...

IMHO this is not a "normal" temperature differential from one side of the engine to the other. I've read that 20 degrees is pushing th bounds of normal and I am well outside that range.

Why would 1 side be so much hotter....both sides are getting ample water supply....and both new risers....would it be safe to say that there is a blockage in the exhaust manifold or a dreaded blockage in the heads or water jacket. Anyone had experience with this exact problem?

 

[BAproject]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

All, I appreciate the help and advice!

I'm looking for a consensus to make my next move;

A) Powerwash the cooling bypass holes in the block (via the t-stat opening in the intake manifold)

-or

B) Pull the heads off and fully inspect/clear heads (if this is event he problem)

Pick one...please

 

[BAproject]

Re: Specific Cooling Question...UPDATE

Re: Specific Cooling Question...UPDATE

Nuthin?