Initial startup cooling system troubles

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KindredSpirit

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Made the first start of my newly rebuilt 340. The engine fired right up and I was starting to go through the break-in procedure when I had to stop. I've got two problems, maybe related.

1. The temperature gauge rose steadily to hot (I'm looking at the stock dashboard gauge.)

2. The radiator top tank filled with the brown, foamy solution shown in the picture.

I did get the timing set to 28 degrees at the 2500 rpm I was using for break-in.

The car is AT so it's got the trans cooler lines.

I used straight, purified water for this initial start.

No signs of external coolant leaks.

The radiator face was evenly warm with the engine running.

I pressure tested the new radiator before installation and it held a steady 15 to 16 lbs of pressure for several minutes so I thought it was okay. Everything in the cooling system was replaced: Radiator, fan, fan clutch, heater core, all hoses, water pump and thermostat.

Any ideas would be appreciated.

IMG_0364.JPG
 
KindredSpirit said:
The car is AT so it's got the trans cooler lines.
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Is the water greasy feeling? Did you mention this because you suspect a cooler leak?

Daughters 96 Jeep (318) had a trans cooler leak into the radiator and the rad fluid had a brownish red color but was greasy feeling and stained the overflow bottle red.

I agree with others, Drain, refill and see what you get after,

Is there signs of water in oil?

Regarding heat (others chime in here Please ) isn't that sort of normal during break in?
 
An update - I used my Mityvac cooling system test pump with the engine off/cool. The entire system held pressure at 16 lbs for several minutes. No leakdown of pressure at all. This isn't my first time starting a new engine and I've never run into this particular problem. I will try the rust cleaner flush and will talk to the engine shop on Monday. Any other ideas would be helpful.
 
Check trans fluid and oil for water. Personally when I fill an empty cooling system I pull thermostat and fill up to it thru thermostat opening. Install stat and housing with hose then finish filling the radiator. This lets air out of system. Also if it’s warm invest in a thermo gun. I’ve got a harbor freight one. The factory gauge can be misleading. Don’t rely on it or oil pressure factory gauges.
 
Regarding the possible trans fluid leakage I wondered about that. The water doesn't feel greasy, and I spilled enough of it on the floor when I tried the 2nd drain and refill to dump maybe a quart on the cement! It evaporated like it was all water - no residue on the floor.

I haven't drained the break-in oil but I see no sign of water on the dipstick. I know that's not a perfect way to spot it so I will drain the oil and start over again.
 
Dubob, good ideas. I'll look into the Harbor Freight tool. This is the first time my gauges have worked since I owned the car so I don't have a good comparison of running temps before I pulled the engine.
 
that's just a little rust from inside the block nothing to worry about . if its holding 16psi for several minutes you do not have any leaks .
 
I bought a HF thermal gun. I'll try another start up on Sunday. For now, I've noticed my temp gauge reads into the "Normal" zone even when the engine is off but key in Run position. The new thermal gun shows 95 degrees at the temperature sending unit (it was hot outside today.)
 
GET SOME TIMING ON THAT THING BEFORE YOU STICK AN EXHAUST VALVE.

28 total is WAY TOO SLOW. Get 40 or 45 on it and let it run.
 
what YR said.
For break-in;
I just rotate the D until the engine rpm peaks, then throw back a few degrees to compensate for the less timing requirement once warm. Then I set the timing after the cam is broke in.
At 2500 and warmed up, the engine may be happy with well over 50*. This is easy to get with a good working V-can.
28* at 2500 is or may be, a good number for WOT power-timing, but you can figure that out later.

As for the cocoa, IDK
 
Exactly. Not enough timing and not enough RPM. Why are people always scared to pull the engine up in RPMS? You need at least 3500 RPM. I always use 3000 as a minimum and vary between 3000 and 4500. You're after splash man. You ain't gettin squat at 2500. Pull some more timing in it and rev it more and let er rip.
 
Thanks everyone. So far I have not connected the vacuum advance. The 28 degrees was a starting setting for mechanical advance at 2500 rpm. I'm sure it goes into the mid-30s with a few more revs. Once I can trust the engine to run long enough without overheating I'll set the total advance.
 
KindredSpirit said:
Thanks everyone. So far I have not connected the vacuum advance. The 28 degrees was a starting setting for mechanical advance at 2500 rpm. I'm sure it goes into the mid-30s with a few more revs. Once I can trust the engine to run long enough without overheating I'll set the total advance.
Click to expand...

The issue with your timing being not as far advanced as it should be points to your overheating problems. Not enough advance in this no-load condition initiates combustion too late to where there's still-burning hot mixture hanging around in the cylinder during the exhaust stroke and going out the exhaust valves and heating up the heads and headers/manifolds.

It's almost impossible to have too much timing with no load at break-in RPMs, at least enough to cause problems. The engine would probably start surging and running odd before anything bad happened. Don't be scared to crank that thing up to 40* for break-in, and/or hook up the vacuum advance during break-in; this is precisely the running conditions that vacuum advance is intended for anyway.
 
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