1985 720 z24 not getting warm

[ElliotV]

I recently purchased a 85 Nissan 720 and have been having trouble getting it warm. I replaced the thermostat(previous owner bought it so I have no idea what temp it is) and it won't get warm except a little bit on the highway and that is only if it is warm enough outside. I was messing with it yesterday thinking the fan clutch might be bad then found out you can't replace it without doing the water pump either then found out it is supposed to have some resistance when it is cold. I did run it without the fan on it for about ten minutes just idling and it started to get warm when it was probably 45f out. Wondering if anyone has any ideas because it isn't even getting hot enough to open the stat. I'm wondering if I can get a more limiting stat to flow less when it is closed. You can also really hear the fan moving when driving it around. Wondering if anyone has some ideas.

[datzenmike]

Clutch fan failure would overheat. If the fan bearing seized it would try to over cool but the thermostat sets the minimum engine temperature.

 

What are you basing the not getting warm on? The gauge? it may be wrong. Little heat from the heater? The core may be covered in leaves or there is a mouse nest in there or the controls are not opening the flap gate inside.

 

If you drive for 30 min and can't hold the top rad hose then it's getting plenty hot.

 

 

 

The thermostat has the opening temperature stamped on the bottom. You want 180F. Forget the previous owners thermostat... could be anything.

 

You better get another one and spend $8 or more on it.

[ElliotV]

2 hours ago, datzenmike said:

Clutch fan failure would overheat. If the fan bearing seized it would try to over cool but the thermostat sets the minimum engine temperature.

 

What are you basing the not getting warm on? The gauge? it may be wrong. Little heat from the heater? The core may be covered in leaves or there is a mouse nest in there or the controls are not opening the flap gate inside.

 

If you drive for 30 min and can't hold the top rad hose then it's getting plenty hot.

 

 

 

The thermostat has the opening temperature stamped on the bottom. You want 180F. Forget the previous owners thermostat... could be anything.

 

You better get another one and spend $8 or more on it.

I was thinking of finding a different stat and I don't know where you would get a 8$ stat. I have installed a aftermarket gauge in addition to the OEM one and have noticed the OEM one does seem to move as it gets warmer. I did cover half the radiator in cardboard and did get it to move but the aftermarket gauge never reached 100f as that is the base temp and I could hold the hose after a 20min drive through town in 55f 

[ElliotV]

2 hours ago, datzenmike said:

Clutch fan failure would overheat. If the fan bearing seized it would try to over cool but the thermostat sets the minimum engine temperature.

 

What are you basing the not getting warm on? The gauge? it may be wrong. Little heat from the heater? The core may be covered in leaves or there is a mouse nest in there or the controls are not opening the flap gate inside.

 

If you drive for 30 min and can't hold the top rad hose then it's getting plenty hot.

 

 

 

The thermostat has the opening temperature stamped on the bottom. You want 180F. Forget the previous owners thermostat... could be anything.

 

You better get another one and spend $8 or more on it.

The heater also gets warm if the truck gets warm so I know that it's good

[datzenmike]

I simply mean don't get a $2.99 special from WallMart. Any auto supply such as NAPA or rock Auto will have them.

[ElliotV]

I ordered the oe style 180 with jiggle pin(no idea what that is for) from napa only ten bucks I was expecting to pay 20 for one

[datzenmike]

Well the jiggle valve will let air out when filling for the first time but mostly it allows a very small amount of coolant past the thermostat when cold, why? well the coolant in the intake is stagnant because the thermostat is closed so while the engine is heating up, only cold water is around it. A small flow through the jiggle valve allows warmed water from inside the block past the thermostat. Otherwise the engine can overheat because the thermostat is still sensing cold coolant and would rely on heat convection, a very slow process.

[ElliotV]

Never knew that is what it was called I always just called it a bypass

[datzenmike]

Yes in fact it is a by pass that serves the same purpose. On the L series engines there is a special by pass on the thermostat housing and a line returning that water to the lower rad hose where it connects to the inlet to the water pump.  If it went into the radiator it would displace an equal amount of cold coolant into the water pump. By recycling the warming water is saved.

[Crashtd420]

10 hours ago, ElliotV said:

I ordered the oe style 180 with jiggle pin(no idea what that is for) from napa only ten bucks I was expecting to pay 20 for one

I had a similar issue for a while.... it ended up being a loose thermostat in the housing... coolant was just flowing past it not through it.... the old thermostat had a really flat base but the newer one installed had more of a crush washer edge.... since installing and even on cold morning I stay right at the middle on my my gauge.

 

I'm not sure if possible on the z24 but try to verify it is nice and tight in the housing... on my L series I was able to reach inside where the hose attached just enough to check....

 

 

[Stoffregen Motorsports]

I skipped over all the replies, so forgive me if I am repeating what someone already said.

 

Scientific method - first is to remove all variables.

 

If you still have the t-stat you removed, put it in a pot of water and bring it to a boil on the stove top. Using a probe thermometer, measure the temp in the water and watch when the t-stat starts to open. Check the thermometer for a reading. Is the old t-stat good or bad? Or different than your new one?

 

Second is to verify the dash mounted electric temp gauge. With the radiator cap removed, place the same probe thermometer into the filler neck of the radiator and make sure it is submerged in coolant. Runt he engine until it gets to operating temp, and check the gauge against the thermometer.

 

Ruler out those variables before you start going down the rabbit hole.

[datzenmike]

For all that work, draining the coolant and removing, testing* and replacing** with new gasket just replace with a new one.

 

 

*stove, pot, thermometer while wife is out of house.

 

**a good chance it needs replacing or why would you be testing it in the first place? If it passes you still have an old thermostat in there.

[Stoffregen Motorsports]

Yes, but I like to know why, so I'm not repeating work.

[ElliotV]

1 hour ago, datzenmike said:

For all that work, draining the coolant and removing, testing* and replacing** with new gasket just replace with a new one.

 

 

*stove, pot, thermometer while wife is out of house.

 

**a good chance it needs replacing or why would you be testing it in the first place? If it passes you still have an old thermostat in there.

Will probably test new stat to make sure it is good. And getting the truck warm to see if the gauge is reading right would be a mission the fastest way would be either cover the whole radiator in cardboard or remove the fan again which chewed up my arm so I will not do that again unless I have to.

[datzenmike]

Just put the new thermostat in and fire it up and let it idle. It will warm up by itself, that's the whole point of a thermostat. It sets the lowest running temperature and speeds the warm up process.

[banzai510(hainz)]

key is making sure the heater valve is open

[Stoffregen Motorsports]

28 minutes ago, banzai510(hainz) said:

key is making sure the heater valve is open

When you're filling the coolant, yes. That is key. Otherwise you get air trapped in the system.

[ElliotV]

Alright haven't had enough time to let it warm up or drive around yet but got the new stat in and it is different from the one the previous owner bought that's for sure the hole is smaller and the plunger deal(not quite sure on the actual name) is a different design so hope it works https://imgur.com/a/cdKqJdb top is new one bottom is the old one.