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1970 1800E. Just had a complete engine rebuild, head and block were checked for cracks, none found. Block was decked, the head cleaned up (It's a later F head by the way) I can go 10-15 miles, the temp gauge is reading good, and confirmed with an IR gun. But soon, the temp starts rising rapidly, I pull over and I find that I am out of coolant!
The engine will hold 10 psi in the cooling system for 10 minutes. Testing for combustion gasses in the cooling system are negative. When shut off before getting too hot, you can hear water boiling in the engine, and the overflow tank gets quite full, well above the max mark. Oil remains clear, no sign of water, and no signs of oil in the cooling system. There are no visible leaks. The tube in the head is in place and positioned correctly. If I stop before it gets hot I still hear boiling. Then when it cools, the overflow tank is empty.
I'm totally stumped.
HELP!
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Are you sure you have good water pump. It may be working ok at idle but slipping as speeds pick up. Seems to me even without pressure in the system it shouldn't overheat if it's not overworked. There's my two cents
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The old pump was leaking, so it is new. I think the overheating and loss of coolant is done, but still don't know why I have no pressure.
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There is a large selection of rad caps based on pressure and how deep the sealing shoulder is. Make sure you have the proper one. Google rad caps when you have a lot of time. Another thing be sure you have the proper thermostat for a Volvo not a generic thermostat.
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I am offering these comments up on the basis of my experience with a 1971 142 E with separate overflow tank with pressure cap on the overflow tank. I am assuming your B20E has a similar arrangement.
You pressurized the cooling system at 10 psi and tested for 10 minutes. Did you pressurize the overflow tank or use the radiator fill port for the test. If you used the overflow tank for the test, did you watch the fluid level in the tank? If it moves at all during the test, you know that you have a leak somewhere. If you used the overflow tank for the test, I presume that you have otherwise checked the overflow tank cap to confirm that it holds pressure?
If you used the radiator fill port for the pressure test, you need to examine the radiator fill cap (because it is not part of the test). I had a brand new radiator fill cap and discovered that it was not sealing. I had to add a couple of pieces of brass shimstock under the rubber gasket to get it to seal.
You said " When shut off before getting too hot, you can hear water boiling in the engine". The only way that water will boil in the engine (if you haven't greatly exceeded the normal operating temperatures or lost a whole bunch of coolant already) is if the system can't maintain pressure. Normally that would send me back to check the pressure cap or the radiator fill cap (which are the only uncertainties left over from your pressure test).
Are you by off chance running deionized water coolant rather than a conventional water / glycol coolant? If so, the water, wherever it is leaking from could be flash evaporating leaving no residual evidence. Water / glycol does not evaporate quickly and as such will generally leave gooey evidence of the leak location.
If you are running water / glycol and it is leaking into the combustion chamber, this will usually show up as white smoke in the exhaust (not steam) and the exhaust may have a sweet smell to it. If the leak is significant (yours sounds like it is) this should be obvious Check for this on a hot day with the engine up to operating temperature. If you are running deionized water, there may be no evidence out the exhaust pipe that you have a coolant leak. Also, if you have a leak into the combustion chamber you should get combustion gasses in the coolant which you say is not happening.
I rebuilt my B20E completely 3 + years ago including all new radiator and heater hoses. When assembled, I made sure all the hose clamps were tight. After some period of operation I was losing significant amounts of coolant. Inspection showed that the new rubber hoses had relaxed allowing a slow seep from just about every hose clamp. Of course, the worst offenders were the clamps on the back of the heater which allowed coolant to leak down the firewall and underneath the thick underlay under the carpet. The underlay I used was mass loaded vinyl with a thick foam isolator which was very effective at hiding what was going on for a significant period of time. That was one sticky mess to clean up!
After checking the above, as a next step, acquire one of those leak test kits with the UV dye and UV light. They can be very effective at tracking down leaks that are otherwise difficult to detect visually.
Others have raised the issue of air locks and the quantity of the refill. If you are uncertain about this, I suggest that you drain the system and then do a measured refill. If your measurement matches the coolant quantity in the service manual, you can be pretty confident that you do not have a significant airlock. If your refill comes up short, then you have an issue to address. A large quantity of air in the system will prevent proper pressurization of the coolant with the potential for localized boiling (explains overheating - doesn't necessarily explain where the coolant is going).
Good luck with it.
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I realize I have not responded to the posts here, my apologies. I'm still not sure what is or was going on, but it seems to have stopped.. for now. Maybe because the ambient air temps are cooler? Or because after blowing three gallons of antifreeze ( 6 gallons mixed) I am running only water for now.
Pressure test: It was on the overflow bottle, though I did not check the change of the water level. Here is a possible clue though, at least for the boiling: Even though the cap tested good, I decided while hot to take the pressure cap off of the reservoir, and I had no pressure! Just for shits and giggles, I stuck an o ring in the neck of the bottle and tried again, a 30 minute drive I still had coolant, but no pressure! Oil is still clear, plugs look normal, not like when you get water in while running. And for the last 200 miles, I've not lost a drop of coolant.
It's a weird one!
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Ron;
All good points by 142G! to that I'd like to add, if fill level is so low (or for some other reason) that Thermostat is not wet, it will not be able to sense Coolant Temp, and so wont open to allow flow to Radiator when it should...again a fill level issue! I suggest you check your Fill Level first!
Good Hunting!
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posted by
someone claiming to be P of Montreal
on
Sun Oct 23 14:33 CST 2016 [ RELATED]
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That last post made some very good points. But before you drain the system to.measure coolant volume just maybe take it for another drive, it's possible you have just burped it a couple of times and all is well.
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If you see nothing in the engine bay and nothing on the ground, there's only one other place.....out the exhaust. I have no clue how. Any smoking or steam out the exhaust pipe?
let us know what you find out. Tom
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You sound like you are more than just a run of the mill mechanic, but have you checked for a wet spark plug?
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Nothing shows on teh ground, even when idling for 30 minutes. I see no steam out the exhaust from the mirror, but will have my wife follow me this afternoon. I'm afraid that despite the checks, it's either the head or the gasket.
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Ron;
I'm following this thread with interest... sofar I have nothing special to add, but I have to say the first thing I thought of was incompletely filled Cooling System...and you haven't stated the amount/volume of Coolant you filled (it should be around a gallon, including filling Heater core)...know also that it takes a while to purge all air from the system and replace it with Coolant, and during that time, strange things can happen in the Cooling System...
Good Hunting!
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Don't understand how it can idle for 30 min. and not overheat, yet in the same time or less driving 15 miles it loses enough water to overheat.
Have you run the heater at full bore? Maybe an air pocket expanding and forcing water out.
Does the IR thermometer indicate that the block and head are evenly warm or is there a hot spot?
Is the radiator cooler at the bottom? Does the bottom hose calapse at higher rpm?
out of ideas for now. Tom
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It's possible that the system has LOTS of air in it. I would certainly try a really good bleed of the system. Heater valve on full hot and the expansion bottle hanging from the hood well above the engine with the cap off. Carefully top up the bottle as the air belches out. Beware boiling water.
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Heater core, perhaps? Or something in that area under the dash (heater valve, heater hoses, core itself?)
--
-Matt I ♥ my ♂
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