Radiator Core Replacement and Sleeve Thermostat Alternatives

[RAC68]

Hi All,

Radiator Core Replacement:
During a member conversation on improving the cooling of a friend's BJ8 at last nights AHS&T meeting, re-coring of the original radiator was brought up. Many of us have had this done but now finding a facility to upgrade the cooling capacity of an original radiator is becoming more and more difficult. Although my experience and upgrade exposure is to a 4-row Core upgrade, I was informed that there is a Dual Density core replacement that better fits the confines of our original radiator and also increased coolant capacity by close to an additional gallon.

Can anyone provide experience of this dual density core replacement? What cost range can be expected for the replacement?

Sleeve Thermostat Alternatives:
As a proponent of using a Sleeve Thermostat to block the cooling bypass, I was informed that the limited availability of the thermostat has increased the price to a ridiculous level. As an alternative, a Thermostat Bypass Blanking Sleeve (https://mossmotors.com/austin-healey-100-100-6-3000/cooling/sleeve-thermo-bypass-blanking) that will close this passage and eliminate as much as 25% of coolant from passing through the radiator. Since most are will not be using their Healeys during cold mid-winter days and can put up with a slightly longer warmup period, is this blanking sleeve a viable alternative? Can this blanking sleeve be combined with a standard thermostat to maintain effective pressure and flow?

Thanks all,
Ray(64BJ8P1)

 

[John Turney]

Ray,

I use the blanking sleeve and a regular thermostat. It works just fine. The blanking sleeve has a couple of 1/8” holes so a monorail amount of coolant can go through the bypass and keep it full.

I’m interested in the new cores also.

 

[RAC68]

Hi John,

Thank you for your response. I have notified my friend to order the blanking sleeve and order one for me as well. As mentioned, I already have a sleeved thermostat in my Healey but, if it fails, paying even the discounted price of $90+++ for a replacement seems ridiculous and will place the blanking sleeve on the shelf … just in case.

Thanks again,
Ray(64BJ8P1)

 

[Deleted member 21878]

Ray
i tried the sleeve and normal thermostat in mine but broke the cover doing so. I tried using two green gaskets but it did not keep me from cracking it. So I bought the sleeved thermostat.
maybe if I had trimmed both green gaskets to fit around the thermostat it might have worked

 

[RAC68]

Hi Drone Dog,

I wonder what is different with John's components and installation that allows him to have a successful installation and what has given you a headache.

John, is your blanking sleeve from Moss? What brand of thermostat are you using with the sleeve?

Was there anything you needed to do to install the 2 units ​

Drone dog, can you answer the same questions?

Thanks guys,
Ray(64BJ8P1)

 

[Deleted member 19315]

Gents, when one fits the blanking sleeve and a standard stat the two small flanges sit on top of each other and as a result stand proud of the head . When the stat cover is fitted and tightened down it can leak or crack. The solution is a thicker gasket or to machine a small counter bore to accept the flange height in the stat cover.
I tried the thicker gasket ( hand cut) then machined the cover in my lathe as a permanent solution.
I have an alloy head and now only use the stat with no sleeve after having the radiator re-cored with a modern high density copper core . I have the original airflow guides and inner wing shields supplemented with a closure plate between the radiator head tank and shroud, I run a Dennis Welch plastic 5 blade fan. I also use a 10 psi cap and an mgb coolant expansion and recovery tank Engine temp only climbs to 190 when sat in heavy traffic on hot days normal running is 170 to 180.

 

[RAC68]

Hi Hassad,

Thank you for describing the real issue and providing your solution. Withough a lathe or a thicker gasket, is it possible and practical to alter the sleeve to allow proper maiting of the 2 components? Would the sleeve rest properly on other supporting structures if its top flange was shaved, or eliminated entirely, to provide sufficient space for the thermostat to assume standard mounting?

Also, you mentioned having the radiator re-cored with a high density copper core. Are you referring to a core with an additional row or the Dual Density core I was inquiring about. If the latter is true, can you provide further information (i.e. manufacturer, etc.).

Thanks again,
Ray(64BJ8P1)

 

[steveg]

I ran the Moss fail-open thermostat with sleeve for a couple of years with two Moss green gaskets with no problems. The lower gasket needs to have the hole enlarged to accommodate the diameter of the thermostat flange, which now stands proud of the head.

Machining the cover flange is great if you have your own mill, but otherwise overkill.

 

[Deleted member 19315]

Steve thats neat, I onlt machined the stat cover because I could. I agree its not necessary if two gaskets or a thicker one works for you go for it.

 

[John Turney]

Correct. Two gaskets, a thick gasket or relief of the housing or head is required.

 

[Deleted member 21878]

I bought the moss sleeve and the moss thermostat. I tried two green gaskets with the inside cut on one of them. But I still did not get the cover, a new one also from moss, down to sit flat. So it cracked as I tightened it. I could have tried again but just went ahead and bought a sleeved thermostat.
Would like toget those parts I have ready for backup though.

 

[shortsguy1]

My blanking sleeve (from Moss) did not sit nicely in the engine recess, so I filed and sanded the outer diameter (of the sleeve lip) a little to get it to rest correctly in the head. I also increased the hole diameter in the gasket slightly (with a careful x-acto knife) so that it was around the sleeve and thermostat, rather than on top of them. Seems to work fine.

 

[Deleted member 21878]

Maybe if I had not tried to tightened it so tight... I can get heavy handed.

I also thought about putting just the sleeve in and taking a socket, tapping on the sleeve flange to make sure it is flat in the recess.... might have helped.

 

[Deleted member 21878]

was doing some research on radiators and wondered if anyone could update the original question for this thread?

my car seems to want to run about 110* above the outside air temp. of course as soon as i hit any traffic, it starts to run hotter. on 90 degree days that does not leave a lot of room before it is running 212.

i have tried different ducting. i have looked at adding an electric fan. i currently run a 6 blade fan and have looked at the 5 blade setup. different people have different views on the last two items but almost everyone agrees a better radiator core is the key.

currently i have a 3 row, staggered, core with 8 fins per inch. guessing that is the best place to start making changes. i looked at the DW black radiator. nice price, but they can not give me specs on it. plus it says "exchange" and i would like to keep an original tank, with the stamping, with the car. if not in it, then with it. i can't tell if their radiators have the stampings.

so i am thinking a recore. was looking for info on the "Dual Density" or "high density" cores. And an idea on how much it costs to have a radiator recored? or if there is a better cost option out there?

 

[Bob_Spidell]

Re-coring the radiator is a good start; the type/brand usually mentioned is 'Excel,' but I can't give you the specs. It sounds to me that if the core gets too 'dense'--to where you're blocking airflow--you might be defeating the purpose.

The best result I got for stop-and-go traffic overheating was with a 7-bladed stainless steel flex fan with a (minimal) outer shroud from BCS. Unfortunately, the fan was so loud at idle--it flattens out at speed to let 'natural' airflow take over--that I removed it and replaced with a Texas Cooler. Not as effective, but not noisy. My BJ8 is only marginally better with heat than your car but, weirdly, runs below the thermostat setpoint until ambient air gets 70degF or higher (as does my BN2 with uprated core but stock fan).

As an aside, I've concluded that serious overheating is likely due to built up crud in the block. If corrosion is bad enough to, say, create a hole between water and oil passages it's probably blocking said passages as well.

 

[Deleted member 21878]

Bob
Thanks for the info.
i have a 650 mile old rebuilt engine that was tanked at the machine shop. i did have a fair amount of rust flakes, lets call them, in the passages when i was putting the engine back together. i tried to clean them out. thought i did a good job but just in case.... i just did a 3 day flush of the system with some Prestone cleaner.

i did a system where i removed the thermostat first. then i hooked the top hose to a pipe that connected to a garden hose. then hooked another hose to the top of the radiator with another garden hose connected to it. that garden hose was hooked to a sump pump sitting in a bucket. the return garden hose dumped in to the bucket so i could recirculate the cleaner thru the system. i also ran the return hose thru a screened funnel so i could collect any debris. for three days i would go out and run it for 15 minutes or so a few times a day and then let sit again. all in, i got very little debris out of the system. So i am hoping my block is pretty good.

i use a 6 bladed metal fan. i have wondered if the 13 blade fan on my TR6 might work better. i know they sure helped TR6's.

i have also read that new engines have more friction so hoping as the engine wears in, it will cool off a little also. even so i expect a better radiator core might be a good move.

Good point though about a denser core.... may need an electric fan anyway.

 

[RDKeysor]

I was able to install the Moss sleeve in my BN7 without incident, but perhaps the gasket I hand made was thicker than standard. I had my radiator rebuilt after buying my car five years ago, but the overheating issue (I'm in Florida) continued. Typically, it came in stop and go traffic. I also fabricated an aluminum surround about 2 1/2" wide that covers the top and sides of my radiator. This car has a Texas cooler, and I have fabricated and installed an air scoop ahead of the bottom of the radiator of the type Steve G has illustrated. A few months back I got into heavy traffic and actually had some coolant loss. This prompted me to install a U.S. sourced (eBay) but Chinese-made aluminum radiator that I had on hand. While nicely made, I found it necessary to elongate the side bracket holes to lower the radiator because the top tank corners and cap were contacting the inside of my hood, the radiator cap touching the cross-brace. There is a limit to how much you can lower a Healey radiator as the hose connection at the bottom left (viewed from behind the wheel) eventually comes down against the frame cross member. In addition to that issue, I found the aluminum faces of the radiator core to be very vulnerable to damage. This was aggravated, I suppose, by the fact that I had the radiator in and out several times in dealing with the fitment issue. The radiator fit very well on the side-to-side dimension, but it didn't come with the fastening nuts welded to the brackets. That presented challenge. I have been driving the car in the high 90-degree weather we have been experiencing here and believe this radiator is superior to the rebuilt factory one I had been using. The only temperature spikes I have seen come when I am backing the car into our two-car garage alongside my wife's car, something sometimes takes a bit of maneuvering. I have seen the temp gauge go to about 212 when I do that, but on the road the running temperature is really good. I hope to give a more definitive report on this radiator when I have more experience with it. I tried several other measures to try to keep the temps down with my rebuilt factory radiator, Water Wetter, etc, so this radiator swap wasn't taken without a lot of effort to avoid it.

 

[dcarlg]

After you have re-cored your radiator, consider fitting a Spal 13 inch low profile pusher fan in front of it. I used the Spal brackets bent to fit the side radiator mounting bolts.

 

[Randy Forbes]

I believe I heard (read, dreamt, who knows...?) that 10 to 12 FPI is considered optimum. While I had never thought about it, as Bob says, it's realistic to think that too many fins could limit the airflow.

You'll be hard-pressed to find a shop specializing in automobile radiators anymore__most use composite/plastic end-tanks__but industrial/marine (stationary engines) and big-rig trucks are still using conventional radiators. The last one I had made in Toledo had waaay more heat exchangers in it for boats and generators than for cars! The proprietor of said shops will probably give you a good technical lesson on the subject (hence most of what I know about them, but I'll admit I've slept since then) and cars can be a lot more forgiving than for their industrial applications.

I also recall that building a top-shelf radiator for a customer's Healey was in the $600+ range, so be prepared for some sticker shock__and you DON'T want him to build you a CHEAP radiator, so don't ask.

The guy even preserved all the original tags (as you'd expect if you're keeping the tanks, but I would still make that stipulation).

Although I did have to paint the shroud myself

I do regret not getting a close-up of the fin or top sheet construction, but hey, look at those overflow hose clamps!

As stated, I think once you've got 1000-2000 miles on your rebuild, it will noticeably loosen up, become freer revving and run a little cooler. Also, I wouldn't be getting too world as you approach 200*F; without a radiator cap the water won't "boil" until 212* and the boiling point is raised 2-3* for every pound of pressure contained in the system. So a 7Lb cap could give you 226*-233* before you're "boiling over." A note of caution though, in my youth (or youts in the North Atlantic region) I tried a heavier cap, maybe 12 or 14Lb (?) and you'd be amazed at how much a stock top tank can change shape! Fortunately, I noticed right away and threw that plan in the can, with no permanent damage to the brass tank!

 

[steveg]

Somebody mentioned a while ago in a similar discussion: the heater core can be the weak link in raising the cooling system pressure. I see Moss sells them for $290 for the sixes; $800 for the fours.