New World Datsuns...

flatcat19 wrote:I love the new avatar, Mike.

Apparently I was on the wrong NWD Banner says. I switched over and my avatar didn't show here so I re set it. I was told I look a little like Walter.

datsunmike wrote:

flatcat19 wrote:I love the new avatar, Mike.

Apparently I was on the wrong NWD Banner says. I switched over and my avatar didn't show here so I re set it. I was told I look a little like Walter.

Hopefully not as eccentric.

ill go on lunch and talk to him. have him take a peak inside... Ill rev the motor out a bit and see if its sucking the hoses closed while i'm there.

I spent about 3 months passively diagnosing my friends overheating 521, heat spikes galore, inconsistent temps, and blew 2 headgaskets. We could not figure it out, and then we noticed something, when we removed the cap, there was hardly any pressure relief, especially when compared to my car.

Well fast forward to the night I got my L19 to fire up, Going to my friends house, Im breaking in my motor as hard as I can, I notice he isnt behind me anymore. I make a U turn, find him on the side of the road. We push the truck into an empty side street. There in the middle of the night I noticed something, Coolant dripping down from a heater hose. I put my finger on it, and it was cracked. Fortunately it cracked right at the water flange at the timing cover. I whipped out the screw driver, loosened the clamp, pulled the hose off, whipped out my pocket knife I always carry, cut the hose back to before the crack, stretch the hose just barely, and clamp it down again. I then also happened to have a gallon of water in my car... And then I hopped back into my car and drove it like a bat out of hell, gotta get those rings to seat!

His truck has not over heated since, he drives it every day.



Water is better at holding heat.
AF will slightly rise boiling temp (but I feel its marginal)
AF doenst rust out Steel plugs (in the block) so if you have steel plugs like I do, make sure to have some AF.
For every 1 pound of pressure, the boiling temp of water increases 4 degrees Fahrenheit. We have 13 PSI caps usually, so 52 degrees higher than 212, or 264 degrees.

Add in a bit of AF and it goes even higher. But this is why when you loose pressure you can over heat/boil over.

I like to run a 70/30 mix, 70% water, during the summer, although because I am lazy, I make it a 60/40 mix, and use it year round.

I see what you mean.

I dont think I am loosing any pressure. The hoses don't have any leaks. I do have spare lower rad hose. I was unable to make it to the rad shop today to tinker around. I am having some other issues personally that I had to deal with.

I'll swap out the lower rad hose tonight, get a new rad cap, swap the thermostat for a fresh one and give it a go and see what happens. To bad I don't know anyone with a pressure tester to see if I am losing pressure somewhere.. Ah well.

The guy at the rad shop will surely have a pressure tester.

As far as the AF mixture...I use 3 gallons of water to 1 gallon of coolant with 2 bottles of Redline Water Wetter all mixed in a huge jug.
On my Maxima and the Sentra I had before that I was using an 18lb radiator cap. No issues ever.

Back in the day I had a 1978 Lincoln Town Car. My temp gauge was always up and down. Tested AF protection-straight anti-freeze.
Drained and flushed out rad, block, and core. Filled with 50/50. It would still fluctuate, but not as bad.
Pulled enough out to add 1 bottle of Water Wetter and installed a 17lb cap-never went above normal again.

It's probably the wrong way to do it but I always run 1 gallon of AF and fill the rest with water. This is with any car I own. Never had any real trouble, just a little fluctuation. And I live down here where it gets so hot the air sticks to you. Do you have a heater/heater core? Leak in that line maybe?

I haven't noticed any fluids on the floor. A pressure test would be tits, though. Ill start with a new rad cap and thermostat, lower rad hose. See where I go from there.

I do believe this is a radiator issue.

It stays cool at idle, and slow speeds around town. at 60+ and in hot areas, the temp rises. I think the radiator isn't able to keep up with cooling. When I had him fix a hole I think one of the lines was plugged but I can't recall...

A bad fan would be not cooling at idle/low low speeds, a bad thermostat would be hot all the time, maybe slightly cooler at highway/freeway speeds but not a lot. Blown head gasket usually in my experience is hot all the time, too.

Just ordered some gaskets for my rebuilt motor. Once I get that thing finished up I will be checking on a different radiator. maybe one out of a B12/B13 sentra. I'll have to do some measurements, or a used b210 radiator (but being they are 35 years old, new may be the way to go)

What you're describing does sound like a radiator flow problem. New radiator should do the trick.

There is something that you're possible missing. . . I had this occur to me on a 1980 Chevy LUV truck (Isuzu's are crap!). I had similar heating, under-heating and over-heating going on. I did everything to it. New water pump, new radiator, new thermostat, new head. . . I was scratching my head trying to figure out what it could be. Finally took it to a radiator shop, turns out it was the vacuum advance on the distributor. We swapped the distributor, and all problems went away! It's a thought, and just one more thing to check on. . . Sorry.

Don't be sorry! I supposed that would cause it to do one of two things or both maybe? It would be running rich. But, i adjusted the air/fuel mix, and also it could cause it to be advanced if it was lodged in the advance position. I have a timing light and its free to check

izzo wrote:Don't be sorry! I supposed that would cause it to do one of two things or both maybe? It would be running rich. But, i adjusted the air/fuel mix, and also it could cause it to be advanced if it was lodged in the advance position. I have a timing light and its free to check

Well, then I'm glad I brought it up!

At speed, vacuum advance is roughly equal to manifold vacuum. Heavy foot low vacuum low/no advance. Light foot steady speed some advance. If your advance isn't working, the engine will act retarded and will start the burn late. Most of the fuel will be burning when the exhaust opens and the heat absorbed into the coolant around the exhaust ports. Possibly this is it.

Take the cap off and such on the hose to the vacuum advance can. The rotor should turn about an inch and hold until released. Check for cracks in the hose that would leak vacuum.


Tim, I don't think I mentioned this but watch the lower rad hose and rev the motor, rev it really high. Does the suction from the water pump collapse the hose? This would definitely restrict flow out on the highway but not around town/idling.

datsunmike wrote:At speed, vacuum advance is roughly equal to manifold vacuum. Heavy foot low vacuum low/no advance. Light foot steady speed some advance. If your advance isn't working, the engine will act retarded and will start the burn late. Most of the fuel will be burning when the exhaust opens and the heat absorbed into the coolant around the exhaust ports. Possibly this is it.

Take the cap off and such on the hose to the vacuum advance can. The rotor should turn about an inch and hold until released. Check for cracks in the hose that would leak vacuum.


Tim, I don't think I mentioned this but watch the lower rad hose and rev the motor, rev it really high. Does the suction from the water pump collapse the hose? This would definitely restrict flow out on the highway but not around town/idling.

Yeah I think that was mentinoed sometime before, and by other people when I looked around on ratsun. I replaced the hose with a new one just in case.

I went home last night, temp gauge was about half way up which isn't normal really for a round here like in the beginning of the thread. I shut her off, got out and saw steam comin from under the hood and smelt a sweet smell in the air...... Popped the hood, top of the rad was wet, driver side / inside fender was wet (probably from roads but can't prove it) and then spray on the firewall. Pressure is escaping, on top of the fluids. This isn't like before. Before it would just get too warm, now its shooting shit out. I'll flop a new cap on and see if that will buy me some time.

All good suggestions, thanks guys...

I should do a compression test, just for shits and gigs. I did a head gasket 6 months ago, could be blown again or head warped (i didn't check). Could be a faulty rad cap, I'm leaning towards radiator tho. It pooped out on me once and it got pretty hot on a 4 hour run to vancouver and back. I need to get off ma butt and start doing free tests, like timing, vac advance, compression etc..

Ideally I'd just like to replace the radiator anyways. Even tho it was fixed by a shop once and flushed real good, doesn't mean it's not bad. Plus I think a tube was plugged on purpose as it was a tiny stream of water shooting out of a hole that appeared.

I run AF and water mix, it looks about tits on comparing to other AF/water mixes I see. Tho when it leaks out on the top of the rad, I see rust forming... And it was painted when it was gone thru 6 months ago.

Tuesday I received my gaskets for a rebuilt A14 I have sitting in my garage. I think putting it together, along with a new rad would work wonders on the girl.

my b did the same thing until I got a new radiator. Then it was awesome temps until my motor took a shit haha. I wish you the best of luck!

Jamee wrote:my b did the same thing until I got a new radiator. Then it was awesome temps until my motor took a shit haha. I wish you the best of luck!

Thank you! I checked it out. that new rad is awesome looking. I just cant pony up 260 for the rad. I got my CC i need to pay down a little bit, and insurance is due plus rent. So i'm SOL.

Gray has a rad out of a sentra or w/e he bought. fit in his 1200, there for should fit in my B, with a little work of course. I'm almost positive its the radiator, but the saying goes, don't throw money at yo shit! Do some tests first, then fix it.

Can't say how many times i dropped some dough on new parts and it was something else

the sentra radiator is 50 bucks shipped That's a smoking deal for a new alum/plastic radiator. even if it is a meh brand. I guess if I got the rad and it didn't fit I could throw it up for 50 bucks and at least get my money back one day, maybe