521 Over heating problems

[banzai510(hainz)]

I was watching Roadworthy Rescue and he adjusted the timing on the OHC 66 Tempest and was good! mpo more over heating. How true? Idk

[datzenmike]

Proper timing, all the combustion takes place in the combustion chamber with piston close to TDC. Late timing (retarded) exposes more cylinder wall and exhaust port to higher temperatures and this heat is absorbed by the cooling system. tremendous loss of power too.

[Matt H]

Hey sorry for the delayed reply. I had been travelling these last couple of weeks...

Thanks everyone for chiming in. So I just pulled the radiator and flushed it and it it appears to be running again now! There was no obvious blockage - although a fair amount of dirty water came out from the very bottom of the radiator. I flushed through a few times until it ran clear. Bizarrely there also sounded to be something metal rattling around inside the radiator.

It was idling a little hot on the driveway still (maybe 2/3rds) but after I took it around the block a few times it mellowed out. I'm a little surprised its running smoothly now to be honest as it was overheating pretty quickly before pulling the radiator. Is it likely that there was just trapped air in the system as a result of the radiator running low?

Also shot the thermostat housing and its reading at 176 after it had been running for a while.

Thanks all 🙌

[datzenmike]

The rattling is just solder droplets.

 

Should read about 10 degrees higher at 185F.

 

The highest point in the cooling system is the thermostat housing and the engine is tilted up at the front. Any air will work it's way there even without a push from the water pump. The L series thermostat is mounted horizontally so as soon as it opens, air escapes to the top tank of the radiator. Just check the radiator level after warm up after re-filling it and top up. Always use distilled water.

 

Get a coolant recovery radiator cap and run the overflow hose into a container that is 1/2 full with the hose submerged. On hot days or often during the heat soak after engine shut off the cooling system can over pressurize and expel coolant. This system catches it and when the engine cools, the air it the top tank contracts and sucks the coolant right back in. This keeps the radiator topped up automatically. I used to top up every week (this dilutes the anti freeze) and ended up running the rad about an inch low to allow for expansion. With the recovery system I now top up a cup once a year.

 

 

[Matt H]

ok thanks @datzenmike  I'll look into installing an overflow system. Is a coolant recovery radiator cap essentially just a closed cap with no pressure release? Do they have different psi ratings?

I'm not sure what it is with my car but it has this great habit of when I fix something - something else immediately goes wrong hahaha.

I might put this under a new thread but since fixing the overheating issue i'm not noticing the car is having a harder time starting. It tends to struggle to start now and when I try to rev the engine or use the choke it dies. It takes me quite a few attempts to get it running. After it's running its typically fine however I am noticing occasionally it can stutter when pulling away in first gear almost like its miss-firing or something. Do you think perhaps where coolant leaked all over the alternator it might of messed it up or could it be the starter and or spark plus are on the way out?

 

[datzenmike]

Has to be a special coolant recovery radiator cap. Back in the day I just grabbed one in a wrecking yard.

 

[banzai510(hainz)]

make sure intake and carb are snug also

[Stoffregen Motorsports]

14 hours ago, Matt H said:

I'm not sure what it is with my car but it has this great habit of when I fix something - something else immediately goes wrong hahaha.

That's just old cars in general. You don't notice the other problems while you're focusing on the others.

[Matt H]

So I noticed the temp was starting to creep today. It looks as though the top radiator hose was starting to fail / come loose as the was residue and dripping inside the engine bay. I'm was curious if this was just a loose clamp or if the coolant system was over pressurizing for some reason. It looks as though either the head gasket or valve cover gasket might also also leaking and potentially around the water pump. Is it likely this is related? (I changed the stat around 2 years ago)

 

 

 

 

 

 

 

 

 

 

 

[Stoffregen Motorsports]

Not likely related. The pics showing the water pump and head/block look like oil mess,not coolant.

 

I wouldn't be surprised if the soldered joint at the radiator was cracked. You may want to pull the radiator and have it leak tested. Or just tighten the hose clamp and see if it goes away.

 

If you didn't run the motor out of coolant, you shouldn't need to worry about engine damage...yet.

[MikeRL411]

44 minutes ago, Stoffregen Motorsports said:

Not likely related. The pics showing the water pump and head/block look like oil mess,not coolant.

 

I wouldn't be surprised if the soldered joint at the radiator was cracked. You may want to pull the radiator and have it leak tested. Or just tighten the hose clamp and see if it goes away.

 

If you didn't run the motor out of coolant, you shouldn't need to worry about engine damage...yet.

 

Remember those rattling sounds?  You have just gotten the source.

[Matt H]

Hi both,

Thanks for this - I'd say your diagnosis looks pretty on point. I tightened up the hose and took it around the block today and can see its still leaking. I'll pull the radiator and have it pressure tested as mentioned. If it is the soldered joint - Is that something that can be easily repaired or am I better off looking for a newer replacement radiator? Am i right in thinking these top hoses are also hard to find a replacement?

 

 

[Stoffregen Motorsports]

Any radiator shop can fix a leaky joint. They might suggest recoring the radiator, and if you do that, go with as thick a core as you can fit in those tanks. New radiators are not as good of quality as the old, original bras tank radiators. If you are lucky enough to find a brass replacement, it will cost you hundreds of dollars, like $500.

 

Google "molded hose guide PDF" I think it's Napa, but it may be Gates. I found it - https://www.gates.com/content/dam/gates/home/knowledge-center/resource-library/catalogs/gates-molded-coolant-hose-id-guide_web.pdf

 

Starting around page 44, the hoses are listed by inner diameter. You look at the image, then compare length and see if you can identify anything that might work. I have used this guide dozens of times to find hoses. Sometimes I buy a hose that is much longer than what I need, but will have the right bends in the span, and then just cut off what I don't need.

 

Is there a place we can put this link so I can stop having to look it up? Like a reference section?

[datzenmike]

Hose looks kind of puffy. If replacing just slit it and peel it off. The reason it might be leaking is form pulling and twisting the hose to get it off. Only soft lead holding the neck to the radiator tank.

 

Empty and lay face up. Wire brush the crap off and clean it up. Heat the solder with a torch and twist the neck off. Quickly wipe with damp cloth to get any excess solder off both parts and check the fit. Now's the time to lightly hammer out any damage. Set in place, a little soldering paste and heat with torch and chase the melting solder around the joint.  

[Matt H]

Thanks both - much appreciated! Will report back with an update shortly.

Looks like I can source a new one locally

https://www.oreillyauto.com/detail/c/gates/engine-cooling/radiator-hose/b0a07a12b12d/gates-radiator-coolant-hose/gat0/20776/v/a/16463/automotive-truck-1971-nissan-521-pickup?q=radiator+hose&pos=0

 

Edited May 15 by Matt H

[banzai510(hainz)]

those hoses are still avail and I always buy 2 anyways of both upper and lower.

 

Champion does make 510/521 radiators, but you need a 1/4 spacer to keep it off the upper core support ledge.. I got 1/4 plastic spacers from a hardware store. Best to glue them on rad first to make it ezer to intall.

[Stoffregen Motorsports]

17 hours ago, Matt H said:

Thanks both - much appreciated! Will report back with an update shortly.

Looks like I can source a new one locally

https://www.oreillyauto.com/detail/c/gates/engine-cooling/radiator-hose/b0a07a12b12d/gates-radiator-coolant-hose/gat0/20776/v/a/16463/automotive-truck-1971-nissan-521-pickup?q=radiator+hose&pos=0

 

Curious, did you find the hose using the hose guide?

[Matt H]

@Stoffregen Motorsports I noticed someone mentioned Oreilly's on another thread so I just checked on the off chance. It is in the guide you shared though (Page 93 / Row 196)

Thanks for sharing. I'm sure i'll be using this for other parts

 

Edited May 15 by Matt H

[Stoffregen Motorsports]

Cool. It has been a pretty valuable resource. I should keep it more handy.

[datzenmike]

Don't scrap the old radiator, it's fixable. Someone will need it.

[Stoffregen Motorsports]

I'd fix the original radiator, instead of getting a Champion.

[Matt H]

OK so I removed the top rad hose and cleaned up the nozzle. At first glance the join looked pretty solid so I thought i'd be clever and not remove the radiator. Instead I just cleaned up the head and installed the new hose. Low and behold the car started to overheat. This time more than before. Is it likely that the stat isn't opening? I replaced it about 2 years ago. 

 

 

 

I was tying to burp the radiator and ensure it was all running smoothly. It didn't really look like it was cycling. If I gave it a little bit of gas you could see it rise and when I cut the engine it nearly overflowed.

For context: The top radiator hose was not leaking during this process and the car was on a slight incline.

I'll likely pull and flush the radiator and change the stat again. I guess that serves me right for cutting corners : |

I still have the thermo gun from the 1st time this started happening a couple of years back so can try that again too.

I don't know if this is my imagination but I swear the temp gauge was hovering around 25% for much longer than usual and took a long time for the radiator to heat up. I had to give it a few revs to bump the temperature 
 

 

Edited May 19 by Matt H

[banzai510(hainz)]

Is that straight antifreeze?  if it is it might run cooler with 50/50mix .  I know my Toyota  pickup did when I swap the freeze out .

 

dont use tap water to mix

Edited May 19 by banzai510(hainz)

[Matt H]

Hey @banzai510(hainz) its a prediluted 50/50 mix

[banzai510(hainz)]

Well its hard to tell that rad look good on the out side.

My 521 did this where I stopped and come back and the fluid be on ground.

If I remeber right I got a new flip up cap and maybe drill a 1/8 hole in the stat.  It went away after while. I thought it needed to bleed. I would run it with the cap off. but alwasy seemed ok then.