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View Full Version : 302 Ford Coolant Temps-need help



John C in PA
05-03-2014, 03:53 PM
Guys, my '92 302 HO Ford runs 125-130 degrees normally, 135 degrees after a hard run before returning to normal. I should be able to make more HP by increasing the water temp to, say 160-180 degrees. I surfed the net this Winter and I cant find a thermostat rated above 140 degrees that is 1.5" diameter. I did find this http://www.summitracing.com/parts/krc-1027/overview/ (mhtml:{FB097613-CCC9-4C70-BDAA-E030F49C2CB3}mid://00000078/!x-usc:http://www.summitracing.com/parts/krc-1027/overview/)). Do you think restricting the water flow using this device would increase the temperature? Other ideas?

Here's a pic of the t-stat I removed 2 years ago. It's only 1.5" diameter so it isn't interchangeable with car t-stats.
79527

Thx guys, John C

jl1962
05-03-2014, 04:49 PM
OK-
I'm not an engine guy, but my 302 (w/ external fresh water pick up) always runs cool - it's Lake George - brrrrrrr.
My engine guys say cool is fine. Isn't oil temp a better indicator? Apologies in advance (and arrears) for general engine know-nothingness.....

gcarter
05-03-2014, 07:58 PM
I know you don't have a lot of options in a 16. That's an awfully tight engine compartment.
My stock answer to anyone that has cold running problems in a raw water cooled engine is to add a closed system, but that'd be difficult, so maybe a oil thermostat might be a good partial solution. Someone on OSO had a couple in "The Swap Shop" for sale a short time ago. They didn't seem to be selling quickly.

John C in PA
05-03-2014, 08:47 PM
Oil temp will tell me if the motor is getting too hot, but so does my water temp guage. I'm looking to increase the water temp thru the heads and block. Besides, my oil pan takes 8 qts to reach "full" on the dipstick so I don't think 200 HP is going to heat it up too much.

As a side note, last year I installed an oil temp guage by placing a "T" into the pipe that runs into the block where the oil press sender fits. Although I ran the motor on the hose for awhile, the guage never got off the peg. Yes, I checked it in a pot of hot water. If I ever have to pull the motor I'll have a fitting welded into the pan (since I still like the idea of knowing oil temp).

John C

gcarter
05-04-2014, 07:31 AM
Someone, or several someones, here know more details about running
raw water cooled engines than I do. But I seem to remember a
somewhat critical "do-not-exceed-temp" of 140*, or so, to discourage
excessive scaling in the water jackets.
I suppose you could raise the temp a little bit w/a t-stat change, but
maybe not as much as you may want.
My suggestion concerning thermostatically raising the oil temp is based
on the suggestion that maybe as much as 25%-30% of your engine
cooling is accomplished in the lube system. And since it's also important
to maintain a certain minimum oil temperature to boil off any condensed
moisture, maybe an oil thermostat would be a good partial solution.

72Hornet
05-04-2014, 09:29 AM
Guys, forgive me if this does not make sense, but I boat mostly in fresh water in NW Iowa. I have open cooling systems in all of my boats. My 302 in the 1968 Donzi has a 140 degree thermostat in it as do most all of my boats. They typically run in the 150-170 degree range during the summer months when the raw lake water is warmer. According to my mechanic, this is optimum as it is actually better for the engine to run a bit warmer as that is what it is designed to do. As far as the water pump information, if you read some of the old Sherwood Manuals, they recommend changing the impellers every 6 months. Here in our shortened summer, we ususally change them every two years. After running on plane and coming into the dock, I usually let the boat run a while before shutting it down to let the engine temperature moderate a bit. It seems to work for me!

Someone, or several someones, here know more details about running
raw water cooled engines than I do. But I seem to remember a
somewhat critical "do-not-exceed-temp" of 140*, or so, to discourage
excessive scaling in the water jackets.
I suppose you could raise the temp a little bit w/a t-stat change, but
maybe not as much as you may want.
My suggestion concerning thermostatically raising the oil temp is based
on the suggestion that maybe as much as 25%-30% of your engine
cooling is accomplished in the lube system. And since it's also important
to maintain a certain minimum oil temperature to boil off any condensed
moisture, maybe an oil thermostat would be a good partial solution.

John C in PA
05-04-2014, 12:49 PM
I seem to remember a somewhat critical "do-not-exceed-temp" of 140*, or so, to discourage excessive scaling in the water jackets.
Thats a new one on me. Perhaps for salt water boats.

I suppose you could raise the temp a little bit w/a t-stat change, but
maybe not as much as you may want.
Believe me George, I've googled every search term I can imagine (I even tried to find a sender built into the dipstick) and I can't find anything except the flow restrictor I mentioned in the OP. I guess 20 bucks isn't a big investment just to give it a try.

My suggestion concerning thermostatically raising the oil temp is based
on the suggestion that maybe as much as 25%-30% of your engine
cooling is accomplished in the lube system. And since it's also important
to maintain a certain minimum oil temperature to boil off any condensed
moisture, maybe an oil thermostat would be a good partial solution.
Thats why I wanted to install an oil temp guage. 8 quarts is a lot of oil for a stock motor to heat up.


John C

gcarter
05-04-2014, 01:19 PM
Sorry John.
I didn't mean to cause you a lot of frustration, just tryin' to help.

John C in PA
05-04-2014, 02:32 PM
Sorry John. I didn't mean to cause you a lot of frustration, just tryin' to help.

No frustration George. Even the famous and talented Ed Donnelly suggested I ask on here :). I decided to look deeper into oil temp guages again. It looks like Harley's and VW's are popular users of oil temp guages. Obvoiusly the dipstick is way too short and not limber. But I did find an outfit in England that has a kit with a temp sender on a dipstick leading to a VDO guage. If it checks out, I'll post that info. (I guess I stole my own thread :yes:)

John C

mattyboy
05-04-2014, 02:59 PM
are you having issues with condensation in the oil? the flow restrictor is for the cool water intake(lower radiator hose) after the pump. in a closed cooling system it would hold water longer in the radiator bringing water temps down on incoming cooling water .not knowing the exact water flow of the omc and risers restricting incoming raw water I would be concerned that it may lead to lack of flow thru the risers leading to burning exhaust hose or steam pockets. without a t stat mine runs at 140 ish this time of year and about 175 midseason it does spike after a hard run when coming off plane to like 200 210 ish for a few seconds. If you do not have moisture in the oil I would not bother .

John C in PA
05-04-2014, 05:18 PM
are you having issues with condensation in the oil? the flow restrictor is for the cool water intake(lower radiator hose) after the pump. in a closed cooling system it would hold water longer in the radiator bringing water temps down on incoming cooling water .not knowing the exact water flow of the omc and risers restricting incoming raw water I would be concerned that it may lead to lack of flow thru the risers leading to burning exhaust hose or steam pockets. without a t stat mine runs at 140 ish this time of year and about 175 midseason it does spike after a hard run when coming off plane to like 200 210 ish for a few seconds. If you do not have moisture in the oil I would not bother .

Matty, nope, no condensation. When I took the valve covers off there was no sludge or whitish oil anywhere.

mattyboy
05-04-2014, 06:23 PM
ok so the motor gets warm enough to boil any water out of it . So where in the circuit would you put the restrictor?

mattyboy
05-05-2014, 09:45 AM
before I did anything I would take readings with a thermal gun and see what the temps are at a few given points to see what you have

1. the outlet on the intake manifold t stat housing
2. the risers mid way and at the dumps
3. the block back front top and bottom

JimG
05-05-2014, 10:47 AM
I know it's a different critter, but my HM 351 always runs cool on the gauge. I asked about solutions several times over the years on this forum, and always got the same answer... just run it, raw-water cooled Fords always show low temps. I have been running this way for eleven years with zero ill effects...:yes:

Just to make myself feel better, I shoot the oil filter with a temp gun on occasion. Oil temps are good and warm after a hard run, so I know I'm not running too cold...

mattyboy
05-05-2014, 04:01 PM
not sure how much hp running another 30 degrees warmer would get ya

but this would put a lil hitch in yer giddy up

http://www.ebay.com/itm/PERFORMANCE-FORD-351W-MARINE-ENGINE-COMPLETE-w-VIDEO-/201083855126?pt=Boat_Parts_Accessories_Gear&hash=item2ed1882116&vxp=mtr


http://www.youtube.com/watch?v=t6_-qwKRMs4&feature=youtu.be

mattyboy
05-06-2014, 08:27 AM
another thought would be try one of these you may need to go to a newer omc/volvo t stat housing after 94 they were a mutual venture until volvo took over all of the I/o business

http://www.wholesalemarine.com/thermostat-kit-for-omc-volvo-160-degree.html?utm_source=recommendations&utm_medium=referral&utm_source=baynote

joseph m. hahnl
05-06-2014, 08:57 PM
I think:rolleyes: you don't want to run water hot like it's anti freeze /coolant. As water turns to steam at 212*F . You wouldn't have a safe margin and you'd pork the head gaskets sooner then later:frown:

John C in PA
05-07-2014, 04:51 PM
another thought would be try one of these you may need to go to a newer omc/volvo t stat housing after 94 they were a mutual venture until volvo took over all of the I/o business

http://www.wholesalemarine.com/thermostat-kit-for-omc-volvo-160-degree.html?utm_source=recommendations&utm_medium=referral&utm_source=baynote

I'll ask them for the OD. In regard to the flow restrictor, the only place I can reach without getting into the bilge is the upper part of the 3" hose. That would build up some additional pressure at the drive pump and possibly starve the belt driven pump. If I go that route, I'll have to keep a weather eye on the water temp guage.

John C

UPDATE: Senility must be setting in :confused:. I checked both Wholesale Marine and Marineengine.com (where I bought the t-stat) and both show its a 160 degree model. So the question is "why does my motor run so cool?".

Ed Donnelly
05-08-2014, 08:02 AM
Have you used a temp gun or portable temp meter?
Could be your gauge or sender is off...............Ed

John C in PA
05-08-2014, 12:52 PM
Have you used a temp gun or portable temp meter?
Could be your gauge or sender is off...............Ed

If I ever do a startup this year :frown: I'll try my surface temp probe on the intake manifold near the sender. I'm thinking 10 deg. F hotter water than the surface of the steel.

mphatc
05-08-2014, 06:27 PM
120-135 is a bit cool . . I ran my 302 at 160 measured with an infra red thermometer, the gauge ran cooler. . this happens because crankshaft driven water pumps often pump way too much water . . especially if you run hard and fast . . a restrictor isn't really a good answer as it increases the load on the impeller. I suggest checking the cooling system pressure, and it it's above 15-18 PSIG a pressure relief valve in the system will dump excess water. Install this after the pump and before the block inlet.

A crankshaft driven pump can force huge amounts of water through the engine, so quickly that it can't absorb heat, and this is what causes the cooling temp to indicate cool, yet the engine temp may be close to good or better than what your gauge indicates..... I know this sounds awkward... installation of a pressure relief valve will reduce flow through the block while slowing water flow, allowing the water to absorb more heat, and also allow for a bit higher operating temperature . .

It's a balance . . . :lookaroun:

Mario L.

JimG
05-08-2014, 09:35 PM
Mario is dead-on as usual. Sounds strange... but it true. My water temp show low but oil temp is right on the money. The head temp are good too... My crankmount pump moves a LOT of water...

donzidon
05-13-2014, 12:16 AM
My boat ran cool due to a sticking thermostat. Aparrently a common problem. Changed it and problem solved. I run in 55 degree ocean water and engine temp is 155. Warms up fine from idle. Not sure I like the idea of a flow restrictor when the thermostat should handle the engine temp.

John C in PA
05-16-2014, 11:08 PM
thx for replies. wont be able to respond for awhile. issues at home.