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1991 454 overheating

S

slauder

Regular Contributor
The other day I was idling and

The other day I was idling and starboard engine over heated. The warning alarm sounded so I shut down. I had a history of a loose belt (never seem to have a second man to help get it tight as I want) so I started back up cooling a while and gave gas out of gear and the temp started to go back down. I motored to dock 20 minutes no problem. I thought that was sign I needed to get down into engine room and tighten belt. Same thing the next day out. Procrastinated doing anything because I winterize end of December.

Yesterday I over heated and no trick I knew would bring down the temp. I checked the belt and even though it’s a bit looser then I like its moving the pump pulley. I opened the sea strainer and its got access to the water (no clogs).

What to check next? I could disconnect the water hose from the sea strainer and see if it picking up the water from a 5 gal bucket…

Could thing be the thermostat that I neglected to inspect this spring?

It’s a tight pain to get to the pump to check the impeller. I was hoping to fish December and deal with the impeller in Jan...
 
"Look for an air leak before t

"Look for an air leak before the raw water pump. like a leaking strainer cover gasket, loose hose clamp, etc.

If raw water cooled, you need to replace the t-stat every year or so.

Jeff"
 
I'll check for leaks that

I'll check for leaks that could suck air.
i am freash water cooled. raw water pump impeller was changed 1.5 years ago. how often to change t-stat if freash water cooled? I've not been doing it last three years i have owned the boat. and i did risers 2.5 years ago.
 
"The other 'easy' item

"The other 'easy' items to check:

water flow out the exhaust pipe consistent with Port engine?

Adequate coolant in the HX?

IR Gun the thermostat housing.

check the tension on the belt spinning the circulating pump (Alt Belt).

Seacock open, fully?

I've never had a thermostat go bad on a fresh water cooled system. Last set got 12 years before they were changed due to major overhaul."
 
"Mark,

Thanks for your help

"Mark,

Thanks for your help again...

RE:
1. water flow out the exhaust pipe consistent with Port engine?

Question 1: Tiara has 5" half under water, so i have to see where i can divert it. any ideas?

2. Adequate coolant in the HX?
Will check

3. IR Gun the thermostat housing.

Question 3: Are cheap guns okay? Recomadations?


4. check the tension on the belt spinning the circulating pump (Alt Belt).
I will check but i did replace the one sitting too far into the pully in spring and i know it a little loose.


5. Seacock open, fully?
yes it is."
 
"PS when i look at IR Guns, wh

"PS when i look at IR Guns, what beam angle do i want...

1:2, which means to get a reading of a 1-inch square you have to hold the gun two inches away from the object?"
 
"That is what I use for heat s

"That is what I use for heat shrink tubing. I think you want one for measuring temperature not creating it.

BTW: Scott, it sounds like you have a classic insufficient water cooling flow problem either in flow thru or pump volume. Your notes sound exactly what I had 2 years ago and there are only 4 major "organs" to deal with.

U - cooler...raw water pump, manifolds and elbows or heat exchangers. Once you can measure these areas, you may find the problem more clearly defined"
 
Scott; do a search on the Sea

Scott; do a search on the Sears site for IR thermometer. They have a couple around $50
 
"Thanks Al/Dave,

Raytek MIN

"Thanks Al/Dave,

Raytek MINI TEMP IR THERMOMETER -0 TO 500F
Temperature range: 0 to 750 Degrees F (-18 to 400 Degrees C)
Laser targeting distance-to-spot: 8:1
Backlit display"
 
"I am in the processs of aquir

"I am in the processs of aquiring a pressure tester from sears.

I am hopeful that the breech is in HX.

I have only looked at the dip stick to check oil.

I wonder if it oil could look good on stick and yet still have 1.5 gals of water in the system. (sitting lower in the pan)?

I think I will do another change Saturday to be sure, unless I get the presure tester I ordered and can verify breach in HX core.

I read test: tells you to remove cap and raw water hose, and pump 12-20 PSI, checking to see if raw water leaks out the nipple.

Questions I have are:
1. raw water intake to HX has port and starbrd hose... assume either will do.
2. What is the nipple? Is that what the hose connects to?

PS:
Acording to my manual for engine, I do have a bleeder value on t-stat housing."
 
"Should only be one raw water

"Should only be one raw water inlet to HX, from the oil cooler. there may be two outlet hoses, one to each riser/elbow. Some HX have one outlet that uses a reducing T to feed each riser/elbow.

My opinion is removing the hose isn't necessary until you determine a leak in the coolant side exists. If you hook up the tester and the pressure falls, you will likely here the coolant escaping. You can then remove the hose and verify that 'lime green' color Ted described.

"Nipple" is the term used for the fitting that a hose usually mates over when smooth.

The color of the oil is a good sign. As long as the oil level has not risen, you should be okay.

I'd be inclined to hold off on the change until AFTER you find the leak."
 
"Scott,

Regarding the oil l

"Scott,

Regarding the oil level, I just went through this the other day. I dumped at least 2 qts of coolant into the top half of the engine when removing the intake manifold.

The dipstick looked fine and the level wasn't too high until I ran it. That's when it turned ugly.

Just an FYI, you've already run it so hopefully not applicable to your situation.


Bob"
 
yea I am very concern...

Th

yea I am very concern...

The manual said to remove the engine and drop the pan if I cannot find a HX core leak from and pressure test.

And then if you cannot find the leak problem you need to disasemble engine! That way out of my leage.

I keep clinging to a couple facts in my favor:

I ran for 30 minutes Saturday at 12 and 6 RPM.
Oil checked good after. Also was running the other day and lost 1 gal before i knew lost coolant issue (thought was lose belt).

I have been talking to God this week and an hoping that I got away with it this time.

Unfortunatly I never did hear voices back? Guess I wait until Saturday.
 
"Mark,
The highest part of th

"Mark,
The highest part of the raw water side is the outtake nipple that is a tee that goes to the risers. So for presure test I remove one of the hoses and look for raw water to exit the nipple after I pressureize the system to 15 psi?"
 
"I'd check the cap for a p

"I'd check the cap for a pressure rating. I want to say my old OEM system had a six or eight pouund cap. If so, I don't think I'd go much over 10 psi.

On the hose, either one should be adequate. I'd be a bit concerned with the cold (on the east coast anyhow) if there was raw water left in the system tonight. If it is frozen, it could take a while before you see any fluid.

The other step that is good is to be quiet and listen. It isn't uncommon to have to seat the adapter on the tester a few times to get a good seal. don't forget to make sure the relief vlve is seated as well."
 
Having had a few owners our bo

Having had a few owners our boat had several caps in a "Parts" box and one of the caps on the heat exchanger was a 15lb automotive cap. The new caps I bought are 7psi
 
"I have power and an electric

"I have power and an electric oil filled heater in engine room. Its set to be 42F so I dont have to worry about the freeze.

The book said to introduce 12-20 PSI but the cap is reated at 7 PSI as you noted? Maybe I can get the old 15 PSI cap from car? Al is that what you mean, get a 15 for the test?

Another question is the thread sealent. I book make s reference to "Perfect Seal thread sealant"... is that still the best to use?"
 
"Scott; at the rate you were u

"Scott; at the rate you were using coolant, just pump up a bit, and you will see that leak. You won't have to even hit 7psi.
thread sealant: which threads? PST is great stuff."
 
"Dave,
I am planning to corre

"Dave,
I am planning to correctly diagnose the HX core leak via the pressure test AND then replace the HX.

Do I need the thread seal for the drains?

Book indicates to drain freash water system. Drain plugs are in Exhaust Manifolds, Cylindar blocks, and HX. Also threads for the t-stat vent.

I think I have seen all drains except cylindar block (book does not show picture of them).

Do you know where they are?

Scott"
 
"block drains are low, roughly

"block drains are low, roughly mid point on each side. Obviously, above the oil pan. Why are you draining all the coolant? Is it two years old or older? Yes, PST is good on all the pipe threads."
 
"Dave's steering you good.

"Dave's steering you good.

I'm sure perfect seal is referencing a specific brand. Quicksilver used to offer "perfect seal" which was a repackaged version of GM's general purpose gasket sealer. Loc-tite's PST is great; I use it or the permatex thread sealant with teflon...pretty much the same stuff.

The block drains - one on each side. Going on memory, between the two aft most 'freeze plugs'. I would not drain the block unless you have to change the coolant. Best test for the coolant is the alkalinity test - litmus paper or some pool test kits. In essence, they want to make sure the pH is above 7.0. By how much, I couldn't tell you, but I'd guess that 7.4-7.6 or higher is adequate."
 
"This is a thank you report fo

"This is a thank you report for all the help you guys gave. Also a couple embeded questions


Very pleased to have two new great tools and more knowlege and experience for diagnosing problems. The tools proved well worth the money.

I was at the boat yesterday and planning a HX swap. Only problem is the pressure test didn't show HX core breach at 7PSI.

I pumped the pressure up to 20 PSI (12-20 was in book) and contorting my body against the cold engines. Amazing how my hot running engines were limiting my abilty to inspect areas.

Also the extra PSI exagerated the leak at hose clamp on the bottom of the HX (startboard side of the startboard engine). HX freash water outtake. Also at 20 PSI saw a very small drip from HX on one of the inputs from manifold.

Replaced clamps and started the fill process.

Opened the t-stat vent and heard "glug glug" sound as air released some traped water. I never saw the water come out the vent as you folks and book indicates should happen?

Started and ran engine at 1200 never touching the throtle, let it increase to ~1900 as it warms (is that the choke off that brings the rpm up?)

Measured 230F at port exhaust mani again while warming but since cap off HX saw air bubble up twice at around 1900 RPM. Using the gun, measured the temp dropping down from 230F to 168F and stable now. Also had read blerb in book to run at 2000 for ten minutes to remove trapped air.

The new IR gun is also helping to showing me the heat disipation from my oil filled electric heater from close sides to far sides of engines. A good 10 degrees difference.

I didnt drain the water but maybe should as its same for 3.5 years I have owned the boat. Always change at two years? Will PH test today.

I still may fish one more time this year!
Kinda spooky to see the ice forming on top the water just 30 feet away last night on other side of dock. bubblers on boats both sides of me are doing my boat too!

Thanks again folks!

Scott"
 
"Scott,

I was hoping to kee

"Scott,

I was hoping to keep our boat in longer as well and we were about to buy a "bubbler". I started to see the people who operate marinas...SLOWLY starting to disappear. I was watching weather and when the snow came last week, I thought "great, with another storm bringing bigger snows in, I'll be trying to find a lift operator and they will all be in FLORIDA !"

So ...it came out"
 
"Scott:

glad you found thos

"Scott:

glad you found those tools a worthy investment. I'd bet you will benefit more from the 'experiment' learning how to use them. I'd venture a guess and say you saved enough going DIY, over a service call, to buy the tools and dinner and still have savings.

Seeing coolant come out the bleed hole usually takes time and doesn't always happen when filling. I've been known to leave that plug loose with the engine running until it weeps, then tighten down.

If the factory manual said you can go to 20 psi, you are safe...I think Stant suggests 4 psi over the cap's nominal rating. You learned why at the boat.

The engine speeding up is probably two things - the friction reduction as it warms and the mixture going from rich to much closer to optimal.

You'll never go wrong changing your coolant every two years as long as you use the 'old' green stuff. Some of the newer 'flavors' are for autos only. You can have it analized, just like the oil, but I've found it is not cost effective. If antifreeze cost keeps going up, I'll revisit that one.

Best thing about fishing this time of year is you'll see very little competition. When you get one of those "spring like" days in the next few weeks, you can sneak out and catch a few. I've caught several nice stripers between thanksgiving and Christmas."
 
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