Moparts
Shroud / fan clutch Q's
Posted By: Wirenut
Shroud / fan clutch Q's - 04/12/19 05:27 PM
I have a 65 b body street car with a 71 340 in it .
For the last couple of years the engine temp seems to be getting higher and coming up more quickly and if left to idle will boil over.
Over the road the temp will drop to 150-170ish..
I have replaced the stat, the coolant , the water pump , have checked the timing , changed the cap .
It makes and holds pressure .
I plan on changing the stat again as I have had terrible results from stant stuff lately. Been having good results with MR G stats.
I was going to pull the radiator and see if I can flush it .
There is no shroud and I will put one on.
There is no fan clutch and would like to put one on.
Questions.
Are all 22" small block shrouds the same ? It has a parts store radiator that has the tabs for the shroud . If I had to guess I would say its a duster 340 radiator .
Best source for a reasonably priced shroud ?
for a driver ?
Does anyone know the brand and # of the shallowest clutch ? I have seen it posted from time to time but never jot it down
Thanks
Posted By: RapidRobert
Re: Shroud / fan clutch Q's - 04/13/19 01:27 AM
typical partly plug rad will show up at higher RPM's (eng producing more heat/rad cant keep up). I'm trying to decipher what is changing but nothing is jumping out at me. You're sure nothing has been changed/altered? It ain't making sense (but we love the toughies!). If it was OK WO a shroud then it oughta stay that way but SOMETHING is slowly changing/deteriorating & that is what we need to figure out. The cooling system will hold psi when hot/set overnight?
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/13/19 03:54 AM
typical partly plug rad will show up at higher RPM's (eng producing more heat/rad cant keep up). I'm trying to decipher what is changing but nothing is jumping out at me. You're sure nothing has been changed/altered? It ain't making sense (but we love the toughies!). If it was OK WO a shroud then it oughta stay that way but SOMETHING is slowly changing/deteriorating & that is what we need to figure out. The cooling system will hold psi when hot/set overnight?
Yeah that’s pretty much it . Figure I would try a shroud. The only other factor is she’s getting older and has racked up 75 k or so since the last rebuild
Posted By: ahy
Re: Shroud / fan clutch Q's - 04/13/19 05:50 AM
I think you are on the right track. It wants/needs a shroud for low speed cooling performance. That is first step.
The radiator could be getting plugged as well. In my experience, parts store radiators for classics can be weak to start with and some deterioration will make them non functional. Another check would be the fan clutch. Inspect for loose/sloppy and feel for air flow in front of the radiator are the best checks I know.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/13/19 01:32 PM
I’m trying to get someone to answer the shroud and clutch questions
Posted By: RapidRobert
Re: Shroud / fan clutch Q's - 04/13/19 01:38 PM
It might be the Hayden #2765 that is 2.67" long. EDIT & the cooling psi holding I was thinking of a potential slightly increasing head gasket leak. (& it may be as simple as the rad). I would want it at 185 or above with a confirmed accurate gauge.
Posted By: Supercuda
Re: Shroud / fan clutch Q's - 04/13/19 02:08 PM
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/13/19 02:20 PM
Ok thanks .
Way out of the budget for this ride.
Perhaps it’s time to fab or modify something.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/13/19 02:21 PM
It might be the Hayden #2765 that is 2.67" long. EDIT & the cooling psi holding I was thinking of a potential slightly increasing head gasket leak. (& it may be as simple as the rad). I would want it at 185 or above with a confirmed accurate gauge.
Thanks I will check it out
Posted By: Supercuda
Re: Shroud / fan clutch Q's - 04/13/19 02:29 PM
You should also remember that in 70the lower outlet changed. If you are running an aluminum water pump then it's the later style, if you are running an iron water pump it's the early style,
If you are indeed running the later A body radiator like you think then
https://www.classicindustries.com/product/1972/dodge/dart/parts/ma2228.html
Posted By: DaveRS23
Re: Shroud / fan clutch Q's - 04/13/19 03:03 PM
No, all 22" shrouds are not the same. You will need to know what the radiator was designed to fit to get the application for the shroud. And the clutch is a good idea, it reduces drag on the engine, but it will not do anything for the over temp issue you are experiencing. Your '65 did not come with one and it cooled fine then.
A good rule of thumb that we have always used to help solve over temp problems is; over temp only at slow vehicle speeds is usually an air flow issue, while road speed only over temp issues are usually water flow related. Now that is a very general statement, but does help narrow down the problem most of the time.
So, since your car controls it's temp at road speed, it is probably getting enough water circulating. At least at higher than idle engine speed. But it is possible that there is not enough water circulation at idle. Mopar used a number of different sized pulleys on the crank and water pump so different pulleys can be used to vary the water pump/ fan speed at idle. A quick test you can run is to set the idle up 300 RPM or so and see if that helps at all with the over temp.
And before you pull the radiator to have it cleaned, you can take a temp gun and go across the radiator when the engine is up to temp. If the temps are consistent across it, then you don't have any significant blockage. If the radiator has blockages, you will have much warmer and cooler areas. Then there's the fact that it cools going down the road which indicates that the water flow is at least adequate. But remember that the air flow through the radiator does increase substantially at road speed.
Next, how close is your fan to your radiator? A shroud is a very good idea and may end up being necessary, but having the fan close enough to the radiator might do the trick too. Then there's the fan itself. How much air does it move? If you do go to a clutch, you will need a different fan for it. And it will need to match the shroud, if you get one.
Can you post a picture or two of your fan/radiator so we can see what you have?
Posted By: topside
Re: Shroud / fan clutch Q's - 04/13/19 05:01 PM
I had a similar deal going on, things were good when in motion but would heat up a lot at idle/sitting still.
Added a shroud and also swapped WP pulley to a somewhat smaller one to speed that up a bit.
Temp dropped from over 200 to 175. Car never went over 180 again.
No room for fan clutch, it was a pretty rumpity 512" Duster, 26" alum radiator, separate ATF cooler.
As for thermostats, I long ago started checking them in a pot of water brought to boil with a meat thermometer to check opening/closing temps.
Posted By: Triggerfish
Re: Shroud / fan clutch Q's - 04/13/19 05:35 PM
That's the one I'm getting for my 64 Belvedere's 383. They sell the mounts for it, too.
Seen these metal shrouds on ebag, too.
Posted By: topside
Re: Shroud / fan clutch Q's - 04/13/19 07:04 PM
Forgot to add: if the shroud doesn't have to look original for your project, you can adapt one from another same-size core or Speedway sells one too.
Mind the hose & fan locations, though.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/14/19 01:03 PM
Thanks for this . Looks like the right piece and price is a little easier to digest.
G
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/14/19 01:06 PM
No, all 22" shrouds are not the same. You will need to know what the radiator was designed to fit to get the application for the shroud. And the clutch is a good idea, it reduces drag on the engine, but it will not do anything for the over temp issue you are experiencing. Your '65 did not come with one and it cooled fine then.
A good rule of thumb that we have always used to help solve over temp problems is; over temp only at slow vehicle speeds is usually an air flow issue, while road speed only over temp issues are usually water flow related. Now that is a very general statement, but does help narrow down the problem most of the time.
So, since your car controls it's temp at road speed, it is probably getting enough water circulating. At least at higher than idle engine speed. But it is possible that there is not enough water circulation at idle. Mopar used a number of different sized pulleys on the crank and water pump so different pulleys can be used to vary the water pump/ fan speed at idle. A quick test you can run is to set the idle up 300 RPM or so and see if that helps at all with the over temp.
And before you pull the radiator to have it cleaned, you can take a temp gun and go across the radiator when the engine is up to temp. If the temps are consistent across it, then you don't have any significant blockage. If the radiator has blockages, you will have much warmer and cooler areas. Then there's the fact that it cools going down the road which indicates that the water flow is at least adequate. But remember that the air flow through the radiator does increase substantially at road speed.
Next, how close is your fan to your radiator? A shroud is a very good idea and may end up being necessary, but having the fan close enough to the radiator might do the trick too. Then there's the fan itself. How much air does it move? If you do go to a clutch, you will need a different fan for it. And it will need to match the shroud, if you get one.
Thanks Dave a lot of good troubleshooting ideas hear.
Fan is about 1.5 to 2” from the radiator.
Have tried multiple fans no change.
I have a mopar clutch fan in the box but the clutch is too deep.
Can you post a picture or two of your fan/radiator so we can see what you have?
Posted By: DaveRS23
Re: Shroud / fan clutch Q's - 04/14/19 02:30 PM
Yes, I can post a pic or two but it won't help you much. I have a 26" OE style radiator with shroud in an E body with a Hemi. Using an HD clutch with a cut down truck fan. It really moves a lot of air and doesn't have any trouble keeping the big Hemi cool, even in traffic.
I also had a Hemi in an A body, but I used an aluminum radiator and the Mercedes electric fan on that one. That fan moved a lot of air, too and kept that Hemi cool.
I had always used the Mr Gasket hi flow thermostats in my Mopars, but the last 2 that I have had have failed very soon after install. I now use the Stant Superstat or the Motorad Fail-Safes. They do not flow as much as the Mr Gasket thermostats, but I haven't had any failures from them. I always drill a couple extra holes in my thermostats for just that little bit more flow and it makes filling the radiator just that much quicker. It may slow down the warm up time by a little, but the big Hemi makes enough heat that I can't really tell any difference.
Based on the info you have provided, I believe your issue is air flow at low speed. A fan that moves more air, getting the fan you have closer to the radiator, speeding the pump and fan up at idle, and maybe a shroud with it's correct fan would be things I would suggest trying. And again, posting pics of your radiator/fan for these guys to see would be a good idea.
Posted By: Ramtough
Re: Shroud / fan clutch Q's - 04/14/19 02:40 PM
typical partly plug rad will show up at higher RPM's (eng producing more heat/rad cant keep up). I'm trying to decipher what is changing but nothing is jumping out at me. You're sure nothing has been changed/altered? It ain't making sense (but we love the toughies!). If it was OK WO a shroud then it oughta stay that way but SOMETHING is slowly changing/deteriorating & that is what we need to figure out. The cooling system will hold psi when hot/set overnight?
Partly plugged rad can show up at idle also, my 67 Charger always got hot in traffic, parades, in and out of heavy car show parking, had rad re-cored last spring, last year coming out of Moparfest, in line for almost 1 hour, never got over 185 on a 90 degree day.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/14/19 03:52 PM
typical partly plug rad will show up at higher RPM's (eng producing more heat/rad cant keep up). I'm trying to decipher what is changing but nothing is jumping out at me. You're sure nothing has been changed/altered? It ain't making sense (but we love the toughies!). If it was OK WO a shroud then it oughta stay that way but SOMETHING is slowly changing/deteriorating & that is what we need to figure out. The cooling system will hold psi when hot/set overnight?
Partly plugged rad can show up at idle also, my 67 Charger always got hot in traffic, parades, in and out of heavy car show parking, had rad re-cored last spring, last year coming out of Moparfest, in line for almost 1 hour, never got over 185 on a 90 degree day.
That’s impressive!
Going to put the temp gun to it today. I ordered a shroud . I will report back
Posted By: DaveRS23
Re: Shroud / fan clutch Q's - 04/14/19 04:01 PM
A partly plugged up radiator is about the easiest of our cooling problems to diagnose. With a tempo gun, a simple scan of the radiator surface when warmed up will show any significant temp differences. And compromised water flow could impact the engine's temp at any speed. But if your over temp issue was only at low speeds, it is hard to see how it would cool okay under load and at hiway speed. Both of which puts more load on the engine and cooling system than idling does and would require more water flow.
Posted By: RapidRobert
Re: Shroud / fan clutch Q's - 04/14/19 11:44 PM
what's intriquing me is the airflow has remained constant (no clutch fan to slip) but something has deteriorated to where the same amt of air ain't no longer cutting it. Some tuning parameter could have been changed (you made no mention of that when asked). pump has been changed so if it was bad so no loss of water flow (unless the rad is partly clogged but as said it would for sure show up at higher RPM's if it was causing a problem). You have confirmed the temp with a mech gauge? Maybe it needs more radiator.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/16/19 12:56 AM
what's intriquing me is the airflow has remained constant (no clutch fan to slip) but something has deteriorated to where the same amt of air ain't no longer cutting it. Some tuning parameter could have been changed (you made no mention of that when asked). pump has been changed so if it was bad so no loss of water flow (unless the rad is partly clogged but as said it would for sure show up at higher RPM's if it was causing a problem). You have confirmed the temp with a mech gauge? Maybe it needs more radiator.
I think the variable is possibly 2 fold.
When I put this car on the road 12 to15 years ago everything was new . Engine was rebuilt radiator was new etc .. Now it’s got about 80 k on it.
the only other change was that at some point in the last 4-5 years I put a tstat In it. Never had one. I put one in to try and raise the temp over the road . The temp would sometimes never get above 140 ish.. well it didn’t really work as now over the road it will drop to 150-170 ish .
Posted By: Supercuda
Re: Shroud / fan clutch Q's - 04/16/19 02:02 AM
Had the spring for the flapper valve in my exhaust manifold break and the valve wouldn't open. It cause all sorts of hot engine issues that took me forever to sort out.
If you have headers, probably not the issue, if you have manifolds make sure that valve is working and will open.
Posted By: Wirenut
Re: Shroud / fan clutch Q's - 04/16/19 09:49 AM
Had the spring for the flapper valve in my exhaust manifold break and the valve wouldn't open. It cause all sorts of hot engine issues that took me forever to sort out.
If you have headers, probably not the issue, if you have manifolds make sure that valve is working and will open.
That’s something I wouldn’t have thought of.
Valve was removed
Posted By: Supercuda
Re: Shroud / fan clutch Q's - 04/16/19 12:15 PM
Trust me, I didn't think of it either. I found it by accident.
This was my 87 Diplomat I swapped a 360 into. Anyone that's ever seen the stock exhaust setup on that thing knows how well hidden the flapper is by the pre cat.
I replaced the fan clutch, water pump, belts, thermostat, cleaned the block with old school cooling system cleaner (the two part type).
I even found out that I could put the 87 pickup radiator, with HD cooling, into the Diplomat if I used the truck lower hose.
All of that did diddly and I was dropping the exhaust to check for pluggage when I saw the valve was loose and flopping.
Fixed the flapper and it all went away.
It took months of trying to figure it out.
retard timing will make them heat up also.
make sure you have the correct # of vanes on the WP impeller
a/c wp = 6 vanes
non a/c wp = 8 vanes
a/c has 6 vanes with smaller pulley(spins faster) and pumps x amount at idle
non a/c has 8 vanes with larger pulley(spins slower) and pumps same x amount at idle
mixing the 8 vanes with small a/c pulleys can cause pump to cavitate at higher rpms and temps go up. or a 6 vane with large pulley it will not move enough water at idle.
make sure the lower hose is not sucking flat = add a spring inside lower hose.
make sure the fan clutch is spinning at correct speed all thru rpm range or just replace it with a new HD thermos clutch
just a couple things to check that I did not see mentioned.
good luck