Running Hot Since L20B Installed

[rcjone]

Without reading EVERY post (on my way to work) D-Mike's right~ 160 t-stat is way too cold! Your engine won't run @ 160, it's just the t-stat will OPEN at that. If the coolant doesn't stay in the motor long enough it will absorb & transfer less heat to the radiator~ the end result being the stat's almost nonstop cycling, or possibly just staying open nearly all the time. The cabin heater removes some heat as well- even when not in use- also effecting overall running temps.

 

The simplist starting point is the t-stat~ change it out for a 180-190, and see what happens. You don't need that 160 anyway....

 

After that you could have some "tolerance stacking" of symptoms as well~

 

Scott

 

As I recall it is a 180 but with age comes memory loss so will check....

[rcjone]

Check your radiator hoses close, they need to be round from one end to the other. This heater core thing is not the issue, they were put together with a valve to close that circut, the factory thought about this issue. I have had a L20b in my truck for years without issues, I now have a LZ23 in the truck with the stock L16 radiator without any issues, heater fan on or off, hauling heavy loads, while dragging around a trailer that weighs close to a ton itself, BTW, I do have trailer brakes. When the radiator cap is off while the engine is running, do you see the water moving in the radiator?

 

I checked water flow last year and indeed was moving along nicely.

Looked at the hoses recently and they were round. But that was when cold.

[610racecar]

Some more ideas:

 

1. Compression check on all cylinders cold and hot

 

2. Start engine with rad cap off. Let warm up until thermostat opens. Watch for bubbles in coolant while running. May need to rev while watching coolant for the bubbles.

 

3. Pull plugs to see if one looks real clean compared to others (getting steam cleaned by head gasket water leak)

 

Blown head gaskets can be subtle- that's what I am looking for.

 

Marc in Indy

[rcjone]

Some more ideas:

 

1. Compression check on all cylinders cold and hot

 

2. Start engine with rad cap off. Let warm up until thermostat opens. Watch for bubbles in coolant while running. May need to rev while watching coolant for the bubbles.

 

3. Pull plugs to see if one looks real clean compared to others (getting steam cleaned by head gasket water leak)

 

Blown head gaskets can be subtle- that's what I am looking for.

 

Marc in Indy

Replaced plugs 2 weeks or so ago, 2 were a touch rich the others ok.

Will now go start and run the engine and look 4 bubbles...

Just did that, no bubbles but the water pump is working fine. increase revs and the flow rate increases, like it was planned that way or somethin'...

No compression tester to hand. will need to go buy 1

[610racecar]

Replaced plugs 2 weeks or so ago, 2 were a touch rich the others ok.

Will now go start and run the engine and look 4 bubbles...

Just did that, no bubbles but the water pump is working fine. increase revs and the flow rate increases, like it was planned that way or somethin'...

No compression tester to hand. will need to go buy 1

 

That's a good start! A compression tester is a good long term investment. I have the one I bought 27 years ago. The cylinder pressures should be even from 1 to 4. Look for where 2 and 3 are slightly lower than 1 and 4.

 

Good luck- keep us posted!

Marc

[wayno]

I have a wierd question, what thermostat housing are you using, the housing is held on by two bolts into the side of the head, not the thermostat cover that the radiator hose connects to. Is it a L16 housing, or a L20b housing, I found that when I ran the L16 housing without that little hose coming off the front of it, my engine didn't seem to cool properly. It would overheat sort of, but the needle wasn't pegged either. I put the proper L20b housing on with the little hose piped properly and the issue went away.

 

 

[rcjone]

I have a wierd question, what thermostat housing are you using, the housing is held on by two bolts into the side of the head, not the thermostat cover that the radiator hose connects to. Is it a L16 housing, or a L20b housing, I found that when I ran the L16 housing without that little hose coming off the front of it, my engine didn't seem to cool properly. It would overheat sort of, but the needle wasn't pegged either. I put the proper L20b housing on with the little hose piped properly and the issue went away.

 

The housing has 2 bolts, 1 long and the other quite short.

There is a hose coming off the housing but it's blocked off. Been that way as long as I can remember.

[datzenmike]

That hose must or should be connected down to the lower rad hose inlet to the timing cover/water pump. This allows the circulation of hot water from the block past the thermostat so it can sample it and open or close properly. Alternatively you can drill a 1/16" hole in the thermostat. This will also allow water to be forced past the thermostat but it should really be that small pipe going back to the lower inlet.

[wayno]

Fact is I used that L16 housing without the little hose on my LZ23 for a couple days, it acted weird, the engine would start to boil over before the gauge would read it was hot, I had a lot of trouble with the temp. control. When I put the proper housing on, all my problems went away. I changed the thermostat at the same time, so it's hard to tell what actually fixed it. Did the L16s have a hole in the thermostat stock?