Compression questions

[jers36]

I am trying to find what is causing overheating problems on my 36 pickup with the original stock engine. I thought I had it solved last fall but it is acting up again. I bought a new compression gauge and checked the compression trying to determine if I had a blown head gasket. This is my readings from 1-8, 70-65-65-80-70-60-70-70. The truck runs fine except for the over heating, I have read on some previous sites here that this not the best but if it isn't broke don't fix it. I am going to get one of those combustion leak detectors that you put a chemical in it and if it changes color when exposed to combustion gases you could have blown head gasket cracked block etc. as a double check. What do you think of the compression readings? Thanks

[Ken/Alabama]

Remove the upper hoses then remove the belt so the pumps can’t turn. Then fill the engine with water via the water necks until you can see a level. Then start the engine and look for bubbles in the water necks. That will tell you if it’s leaking and which side.

[Lawrie]

And if you give it a rev and see bubles,you can short out each plug and find the cylinder that has the leak
Lawrie

[jers36]

My water pumps are on the top front of the heads I don't think that will work.

[Ronnieroadster]

Watch the water levels in the water outlets of the water pumps on your heads. You need to have the block and radiator as full as the pump outlets so you can watch the water for bubbles in the pump outlets. You can add additional length of hose to the pump outlets and watch the water that way as well.
Ronnieroadster

[Ol' Ron]

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Learn sumpin every day. great forum here!!

[Ken/Alabama]

Originally Posted by Ol' Ron

Learn sumpin every day. great forum here!!

Or clamp a balloon or rubber glove on the water necks and see if they start blowing up.

[rockfla]

Originally Posted by Ken/Alabama

Or clamp a balloon or rubber glove on the water necks and see if they start blowing up.

Ken
Saw this the other day on a Facebook page, was gonna say, why go through all the trouble of taking the hoses loose, just put a nitrile glove/surgical type glove on the neck of the radiator and crank it up and run it, if it inflates? You got problems !!

[Brian]

Any pressure build up from a compression leak will simply vent outta the overflow tube if you put the balloon on neck of radiator!

[Ken/Alabama]

Originally Posted by Brian

Any pressure build up from a compression leak will simply vent outta the overflow tube if you put the balloon on neck of radiator!

Must put it on the water necks on the engine

[Brian]

I know, my answer was to rock

[Bored&Stroked]

Hell, might look like the "hand of the proctologist" sticking above your radiator . . . a new type of "ornament" for age old hot rodders. LOL

[rockfla]

Originally Posted by Brian

Any pressure build up from a compression leak will simply vent outta the overflow tube if you put the balloon on neck of radiator!

EASY, just plug the drain tube off!!!

[Seth Swoboda]

The compression readings are a little low. Tell us more about your engine. Did it sit for a long period of time (years) before you started to run it? What is the condition of your radiator? How are the fins, are they smashed flat? Did your radiator sit without coolant for a long period of time? Is the inside of your engine block rusty? What about your distributor, is it properly timed?

There are a lot of questions, along with the possiblility of a bad head gasket.

[rockfla]

Originally Posted by Seth Swoboda

The compression readings are a little low. Tell us more about your engine. Did it sit for a long period of time (years) before you started to run it? What is the condition of your radiator? How are the fins, are they smashed flat? Did your radiator sit without coolant for a long period of time? Is the inside of your engine block rusty? What about your distributor, is it properly timed?

There are a lot of questions, along with the possiblility of a bad head gasket.

Seth
I had ALL those questions AND "ARE there any thermostats in the system?" from the very start of the post

[Seth Swoboda]

Originally Posted by rockfla

Seth
I had ALL those questions AND "ARE there any thermostats in the system?" from the very start of the post

Some of the cars I have I bought after they had sat for decades. The engine blocks and radiators were long dried out and full of crusty, rusty, scale and dirt. A good cleaning was in order. Also, on one occasion I had to have the radiator rodded out. On another, I bought a NOS service replacement radiator.

On all of them I had the distributors rebuilt and timed.

I have found that a flathead will cool and work fine when all of these systems are working at 100%.

As for the low compression, I put over 1200 miles on a 21 stud with similar compression readings last summer before I pulled the engine and installed a rebuilt engine. It used a lot of oil but I was having fun.

[jers36]

Seth in answer to your question yes this truck has been sitting idle for most of it's life. The guy I bought it from owned it about 5 years. The first year he owned it he had the gas tank cleaned and sealed and the mechanical brakes completely gone thru and rebuilt. He went to some early ford V8 meetings decided that was not his thing and I think just left the truck set in his garage for the next 4 years. I spoke to the owner prior to him and he owned the truck for about 30 years and he said he only drove it around his neighborhood occasionally. That owner bought it from a guy in Georgia who was old and selling his car collection. So setting idle most of the time has taken a toll.
Today I backed it out in the driveway opened the petcocks on the block and put a hose in the radiator and flushed the block for about 30 minutes. It flushed brown water for a little bit and then cleared up. I flushed it last year and put prestone antifreeze in it with some cleaner but that's not what it looked like today. I don't want to pull the engine and rebuild it if I don't have to, it probably has babbit bearings and that could get exspensive.

[jers36]

I forgot to mention the radiator looks pretty good there are no damaged fins they look even and straight, I did see two small places that were repaired but look fine and are not leaking. I put distilled water in it today. I could only put in 14 quarts and it would heat up spit out a little in the overflow tube. Its supposed o take 18 quarts. Will the block fill up with water from the upper and lower hoses on the radiator?

[Ken/Alabama]

Originally Posted by Bored&Stroked

Hell, might look like the "hand of the proctologist" sticking above your radiator . . . a new type of "ornament" for age old hot rodders. LOL

Or some XX Large Trojans !!

[Seth Swoboda]

Jers36,

You might want to remove the top and bottom radiator hoses. Use a garden hose and flush the engine block as well as you can. Try to remove as much loose crud as possible. It might also be worth your time to do a flow check on the radiator. With the hoses removed you can fill the the radiator and observe the rate of flow coming out the bottom. This is kind of subjective but you should be able to tell if the flow is slow or fast. Shine a light inside of the radiator tank and see if any of the tubes are blocked. I'm willing to bet many of them are.

I have this problem with every engine I start after they have sat for a long time.

I'm not discounting the possibility of the bad head gasket. That is worth a check also. I have never had that problem....yet. Or perhaps you have a crack in the block near a valve?

Also, you'll eventually need to put some miles on the engine to try and get the rings to seal better. You might use a liberal about of MMO in the gas for a while.

Don't give up. When you solve your overheat issue, you will want to drive that old truck everyday.

[Planojc]

How are you determining that it is actually overheating?

[jers36]

Planjc: temperature gage shoots up to the top, coolant and steam shoots out the overflow.

[jers36]

Seth those are all good ideas and I will proceed one step at a time and try what you suggested. I won't give up thanks for your suggestions.

[miniceptor86]

Initial timing and advance correct? Radiator cap of the correct pressure I’m using 14# and not belching like the 0 pound that came with the car or the 7# I replaced it with. Initial Timing was off and not advancing. We had exhaust gas in the coolant testing at the tire shop maybe you could find a shop that would do the test gratis or cheap and save some green. Sometimes the leak can show up as white on the effected spark plug(s)

[jers36]

Yesterday I was all excited I flushed out the engine and radiator for about 30 minutes then filled it up with distilled water and a bottle of Prestone super coolant. I started it up and let it set and idle for about 20 minutes the temperature gauge barely moved up, so I took it for about a 20 minute drive and the temp gauge only raised up to about 3\4 of normal and would fluctuate with engine rpm. Great it's fixed! today I drove it to town to the post office about a 15 mile round trip and just when I was about 4 miles from home the temp gauge went to the top and fluxed back & forth between normal & high. I checked engine radiator & hose temperatures with a heat gun & head temperature was about 175 lower radiator hose temps were about 100. I let it cool down and started looking around with a flashlight and found prestone anti freeze seeping out of the radiator fins in two different places. So I need to get the radiator repaired or replaced. Brassworks can build a brand new original radiator for about $1500 or I can try to find someone to recore this one. What do you guys think what would you do?

[19Fordy]

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Recore will save you $$$.

[Bored&Stroked]

You'll probably find that a re-core will be pushing a $1000 - my 32 recore cost me over $800 and that was almost 10 years ago. While a radiator is probably mandatory, you still may be having issues with the engine itself. Maybe check the rest of it out while the radiator is getting done?

There can be a lot of rust/scale in the water jackets, you may have head-gasket issues, etc.. If it was mine, I'd probably pull the heads, inspect the block for rust, sand and crud in the lower parts of the block and clean it as best as you possibly can. I'd put new head gaskets on it and get it ready for the new radiator.

[cas3]

Old brass can become brittle and crack. A new brassworks radiator is expensive, but money well spent, and they are top notch quality.

[Ken/Alabama]

Those temps with the heat gun aren’t hot. So why is the temperature gauge fluctuating? Perhaps a faulty sending unit ?

[jers36]

I guess the way I said that was confusing, you are right, 175 is not hot but normal high on the temperature gage I assumed is about 180 degrees and as I was driving home it was fluctuating between that high mark to pegging out at the top of the gage and back down depending on stop and go traffic. When I was going into town the temp gage was only going halfway up to what I am calling the 180 mark. That is why I started looking for a leak and found them on the radiator core. I hadn't seen a leak there before and out of curiosity I just grabbed the heat gun to verify the temp was in range at 175. I have a new sending unit in the truck.