Overheating...

[Zonargx]

What are your thought on running a 160 stat

[datzenmike]

42 minutes ago, Zonargx said:

 

Your engine is really clean I would love my to look like yours Anyways in my truck the back part behind spark plug 4 I had an a hose connected to the front by the inlet that’s is on the lower control hose. So yea it’s bypass. Your saying I should block those two instead of having them be bypass right?

 

YES!!!!!!  That's hot water that is being directed around the radiator and not being cooled at all and then fed right back into a hot engine. About 1/3 of your water is not being cooled!!! Pinch closed with vice grips and take a ride. Later cut the hose and slip a suitable wooden dowel inline to block flow and use hose clamps.

 

It's just a stock photograph for explanation purposes.

[DanielC]

Did you read my post about ignition timing?

I have driven Datsun 521 trucks since the mid 1970's.  I used a 521 to pull a two horse trailer all over the pacific northwest.  I could pull a two horse trailer, with two horses, up a 6% grade, in over 90 degree heat, wound out in second gear, and not over heat...

 

Datsun 521 trucks are NOT prone to overheating.

 

 

 

[Zonargx]

I need to get a hold of a timing light for that right?

[wayno]

OK, I have a question, you said you are using a 620 thermostat housing, does this housing have a bypass, what I mean is does that housing have a hose connected to it under the thermostat cover?

If it does not have a bypass hose on the lower thermostat housing did you drill an eighth inch hole in the thermostat?

 

I ask because I decided to clean up my engine compartment one day. since I was using a dual SU manifold I decided to use an L16 thermostat housing and delete that bypass hose as I thought it would be cleaner looking, my coolant temps were all over the place after that until it overheated going 50mph down a straight country road, I put more coolant in it but lost the head gasket less than a month later, I put the bypass housing back on it and had no troubles for years, it over heated because there was no bypass and no hole drilled in the thermostat like in the first photo.

The second photo is of the lower thermostat housing with a bypass hose, do you have that bypass hose on your thermostat housing?

[Zonargx]

8 minutes ago, DanielC said:

Did you read my post about ignition timing?

I have driven Datsun 521 trucks since the mid 1970's.  I used a 521 to pull a two horse trailer all over the pacific northwest.  I could pull a two horse trailer, with two horses, up a 6% grade, in over 90 degree heat, wound out in second gear, and not over heat...

 

Datsun 521 trucks are NOT prone to overheating.

 

 

 

I notice the other day that the distributor bottom housing part that goes to the block has marking like for timing or setting it to a certain position.

[Zonargx]

3 minutes ago, wayno said:

OK, I have a question, you said you are using a 620 thermostat housing, does this housing have a bypass, what I mean is does that housing have a hose connected to it under the thermostat cover?

If it does not have a bypass hose on the lower thermostat housing did you drill an eighth inch hole in the thermostat?

 

I ask because I decided to clean up my engine compartment one day. since I was using a dual SU manifold I decided to use an L16 thermostat housing and delete that bypass hose as I thought it would be cleaner looking, my coolant temps were all over the place after that until it overheated going 50mph down a straight country road, I put more coolant in it but lost the head gasket less than a month later, I put the bypass housing back on it and had no troubles for years, it over heated because there was no bypass and no hole drilled in the thermostat like in the first photo.

The second photo is of the lower thermostat housing with a bypass hose, do you have that bypass hose on your thermostat housing?

Yea I believe it did and removed it and tapped it.

i also did not drilled a hole man I feel like an idiot for not doing so. I use to remember doing that to thermostat when I worked with my grandpa at his shop ever since I got a different job I’ve been forgetting about thing like that until people mention it again then I remember 

[Zonargx]

What makes me wonder more is that after I did got the radiator clean put the new pump and fan with clutch I drove home from my parents and the thermostat never got higher than 190 Ans now all of a sudden it’s doing this

 

also mike do they makes anything to block this ports with ought having a piece of hose block in? If not would installing a heater work? I would have to get a hold of the whole fan heater fan assembly as I’m missing it

[datzenmike]

You're making this too hard. 

 

Drain a gallon out of the rad.

 

Cut the hose from the head to the lower rad hose in the middle. Put suitable size bolts or a wooded broom handle in the ends of the pipe and secure with hose clamps. Whatever it takes to stop the flow of water.

 

While it is drained get a 180F thermostat and put it in.

[Zonargx]

Alright

[wayno]

You need to have a bypass even if your just drilling a hole in the thermostat.

When I deleted my bypass and did not drill a hole in the thermostat my coolant temps were all over the place, especially on the freeway, it would go up to the red on the gauge and then all of a sudden drop to almost cold and then start going up again, at times it would calm down and hold steady for a long time just to get hot again for no reason.

 

I didn't really think about it much since it never seemed to actually overheat until it did overheat, I made a couple long trips, one was from Vancouver WA to tri-cities and back with 2 ton of roof treatment, the other trip was when I broke the engine in, I drove from Vancouver WA to Renton WA and back to pick up some parts, it never actually overheated on either of them trips, but after it did overheat it only lasted a couple weeks before I lost the head gasket.

Drill the thermostat!!!

 

Edited August 26, 2020 by wayno

[Zonargx]

Ok so I did check my truck out the hose did no collapse at all I did put some cardboard in between the vice grips and pinched the bypass and it did made it run cooler on my daily commute but it still went pass 190 a lot slower but still did. Today I finally installed my aluminum radiator flushed the engine got to drilled a hole on the new stat and Put half a gallon on concentrated coolant with half of distilled water made sure the stat open up took along time to even get it to go past 130 degrees eventually I just topped it off and drove in home and topped it off when I arrived.

 

as for the bypass I used a broom stick to plug it up and I think it also helped keep it cooler

my temp on the streets stay about 150 ish Ans on the highway max it got to was about 187

 

thanks for everyone’s advice and tips I still need to put a fan shroud on it but not a mayor concern as it doesn’t heat up anymore 

[datzenmike]

Did you get a 180F thermostat? 190F to a bit too high. Running 150F at any time is way too cold and perhaps your by pass hole is too large. Your engine is designed to run in the 180s where the heat expands metal and closes critical clearances. Oil should run at temperatures close to boiling to lubricate properly.

 

 

Also the 'by pass' hole should be small 3/32" would be ideal. Too large and it will be slow to warm up and you may as well not have a thermostat at all.

[Zonargx]

180 And I’ll be driving it tomorrow so I’ll be checking the temperatures better.

[datzenmike]

With a 180 it should be running just above 180 ALL the time so either the hole is too big or the thermostat is faulty.

[Zonargx]

On 8/31/2020 at 4:52 PM, datzenmike said:

With a 180 it should be running just above 180 ALL the time so either the hole is too big or the thermostat is faulty.

So yea after driving it more it’s running at 180 Ans on the highways it goes just a little above 180.

[wayno]

Good to hear it appears to be dealt with.

 

 

Edited September 3, 2020 by wayno

[datzenmike]