Overheating 270 - My checklist- Your thoughts?

[Bill_Wolf]

What is the coolant temperature as taken with a thermometer at operational temperature?

[Cat Man]

That's Great! The pieces are in the correct places and installed correct.

Next we need to be able to measure temperature differences across components with the engine running. The easiest way to do that is with a hand held infra red heat "gun". These are now quite common. An inexpensive one costs about $100 bucks at the auto parts store or borrow one someplace.

With the engine at the Hot temperature, use the heat gun to measure the coolant temp at the front of the cylinder head just before it enters the regulator housing. THis should be the hotest place on the engine. Confirm the reading against the guage in the cab. Same or different? It it really "overheating"?

By aiming the "gun" at the inlet and outlet of cooling components when the engine is hot, the temperture differential or difference points us toward different possabilities. The difference between the top (hot) of the radiator and rad outlet (cold) bottem should be approx 15 degrees F.

IF the temperature differential (called a "Delta" or Delta T) is closer together than 15 degrees across the radiator it points at a capacty issue. IF the Delta T is farther apart than 15 Degrees F it indicates a flow problem.
Remember
Closer=Capacity Issue
Farther = Flow Issue

From there we start to measure other temperture delta's. At some point we'll need to measure some pressures as well.

A couple more simple questions. What are you running for coolant?
Straight Water or Ethelyne Glycol or a mix. What percent mix? Mixed for gas engine or diesel. Corrosion inhibitor added or not.

Tell us what the numbers are and we'll keep going from there.
Keep on the systems approach and you'll find the root cause.

I'll watch for your next post. Hang in there.

Cat Man

[SpookyDad]

Harbor freight makes one for $30.

http://www.harborfreight.com/cpi/ctaf/d ... mber=96451

I have no idea how accurate they are.

Neil G.

[Arizona Ducks]

The radiator is back in with a clean bill of health from the rad shop.

I put a new hand held thermostat in the fill hole and measured temps. At normal operating temps it reads 190 although my temp gauge says 210 which is where it's always read for normal.

It does then want to creep up afterwards unless I let it idle, so I'm to the point where it's got to be the head, head gasket or the intake/ exhaust ports on the manifold were done incorrectly??

I'll try and get the temp gun and give you some more info.

Thanks for the help everyone- I was really hoping it was just going to be the radiator was plugged up somewhere.

[Karoshi]

When you pull the spark plugs are they all the same colour, black, gray white ? all the same or do they differ ?

What colour is the exhaust pipe tail end ?

[Cat Man]

Arizona,

Don't pull the head yet! There is more to check with the system intact and operational.

Karoshi makes a good point about the spark plugs. Ignition timing makes a big difference on temps, but we are ways from that yet. He is correct that higher temps are not always the result of a problem in the coolin g system.

If it was me, I'd still be checking the system and get us some GOOD HARD numbers. YOu said 190 in the top of the radiator but the guage reads 210. A twenty degree guage difference is a HUGE error and we need to get that confirmed and corrected. Then on to the next thing.

Keep the faith!

Cat Man

[Arizona Ducks]

Pulled the spark plugs and they looked good. They've only been in there since May. Little dark and one had some white specs that I flicked off.

The timing was set last week.

[Karoshi]

White specs on a spark plug IS NOT a good thing! You have different conditions in one cylinder, Why ?

Have you tried that leakdown test yet. Either the radiator system or cylinder leakdown ?

[John V Cliche]

Arizona,
What Karoshi and Cat Man are suggesting is correct,
Get a cooling system pressure test unit, you can buy a universal type at NAPA for less than 100 Bucks or borrow one
The cylinder leakdown test will find a bad headgasket ( as well as some "other " issues valves/rings )
The tester will be able to tell you if you are losing pressure, ie bad headgasket or a crack in the head
Another item to check easily is you engine oil ,coolant will make the oil appear to be charcoal in color ( Warm engine)
Obviously you know about oil in the coolant.
Be sure to check your radiator pressure cap or just replace it ( it's cheap ) I think from memory the CCKW needs a 6 pound cap
I/we ( my son ) just had a peice of forrestry equipment overheat on a job
A quick test showed no pressure loss .it turned out to be the CAP..... $4.65 later he was back in service.
Hope this helps
John

[Arizona Ducks]

An update with more questions.

When the engine gets to operating temps...

1. Should there be bubbles coming up in the radiator? There's bubbles and also burps of air. I thought this would mean head gasket?
2. Can you see the coolant flowing when the thermostat opens? It opened, but the coolant never went down and we couldn't really see it "flowing" - just started coming out the top with the cap off.

Does anyone have a part number of the correct head gasket? I believe the one I have and used last time was feltpro 7391 s

Just wanted to make sure that it's the right one and not one that will block any of the holes-

Thanks everyone!