Absolute Frustration on over heat problem. Again.

[lelshaddai]

I am at my wits end. I cannot solve this overheat problem even with 3 manuals(including greenbooks) all of your advice out there and a friend who is a city mechanic.

Things I have done:
1. I have three working thermostats that open in boiling water. One is a 160, two are 180's. Neither type helped or hurt.
2. Replaced head gasket, twice, and changed the holes to match better the water holes.
3. Pulled the distribution tube and increase the slot size to the cylinders
4. New 4 lb rad cap.
5. Timed 10degrees, valve lash correct .020, idle 800rpms, carb rebuilt and set correctly
6. Fan mounted correctly
7. Radiator has 15degrees difference in in temp and out
8. Temp gauge reads correctly
9. New water pump
10. 50/50 coolant mix

So what am I missing? Engine has been cleaned and blown out and flushed.

The only thing I have left to suspect is the water pump. The old one was still working so I guess I will change them out. Yes it is hot here, 102 in the garage but it did not overheat before I had to pull the engine. I have pictures of the latest readings. It did boil over this time.

[dieselderv]

I know nothing about amazons or how easy they are to work on but you said you took out the engine is there anyway you could have a radiator pipe or a breather on wrong or damaged or blocked,don't take it the wrong way not meant to sound as I'm trying to tell you how to suck eggs..

[arcturus]

When you re assembled it all did you "burp" the system? Did you measure the amount of coolant in the system as i suggested?

[Burdekin]

As above. Run the engine up with rad cap off and see if any air bubbles come out. Give the hoses a good squeeze with the cap off. Might be a simple air block.

[Jack Spaniel]

Nice list of things you have done. What you don't appear to have done is get a new radiator, or recore the one you have. I had an old Riley RM at one time and it also refused to respond to all the sort of things you have done. I flushed the old rad in both directions to no avail. In the end I had the rad refurbished and the problem was completely solved.

[arcturus]

To eliminate rad as source of problem take off bottom hose , empty rad and then block hole. Fill rad with boiling water from a jug. When full the rad should have an even hot temperature all over.Run your hand over it.If some parts are cooler than others you probably have a blockage. Check how much coolant is needed to fill rad.

[Ron Kwas]

Jim;

27degrees of temp differential between top and bottom of Rad...I wonder if that is typical...it sounds on the low side...maybe others can post some comparative readings...I've been thinking: Flowrate is low for a while...and this can be caused by resistance to flow/(partial)blockage, or poor WaPu performance or combination of the two...as I've said before, that "new"pump is a non-OE unit with open sheetmetal impeller...unlike the OE pumps with cast, closed impeller...I suspect the open impeller doesn't perform nearly as well with a high back pressure than the closed type...maybe it's time to put the old WaPu back on...has a good flowrate through Rad bee confirmed?

Try to stay positive...you're chasing a subtle issue at this point!

[lelshaddai]

The pump and radiator come off today. I like the rad test from arcturas and the new pump is definitely coming off today and replaced with the old one. I spoke to my mechanic friend and he wondered if the impeller was backwards or off. These are the last two areas to confirm.

[Ron Kwas]

Jim;

I'd like to see a good flowrate through Radiator be confirmed...maybe by plumbing a garden hose to inlet and seeing if full flow comes out of the outlet unimpeded...

...as far as Impeller goes, these are permanently pressed onto shaft, so "backwards" is not a possibility...is the original one an OE pump with cast impeller? I suggest you post pix of both for comparison.

Good Hunting!

[lelshaddai]

Here is a pic of the new pump. The old is the solid impeller.