Loss of coolant summary, please.

Post by **Eddystone** » 30 Jun 2020, 12:54

I have a 98 non-turbo and a 99 t5 turbo. Both suddenly seem to be using coolant quite quickly. No evidence of any leaks. I have seen a SMALL amount of white residue near the coolant reservoirs. Reservoirs are Volvo OEM. Have replace the green caps with reputedly OEM caps. No indication of oil or contaminants in the coolant from visual inspection. Oil in both cars is pristine. Exhaust is normal in appearance. There are no places where coolant is visible and never any leaks under the cars.

Now, I know that there are some idiosyncrasies with the design of the head gasket that are not your typical run of the mill ones. I know that the coolant can be tested for combustion gases, but I don't know of a place that does that. I know that there is a procedure for starting the engine cold and monitoring the coolant levels.

Lastly, I am going to pull the carpets back and check for hidden heater core leaks although I have personally replaced both cores.

Could someone either summarize all of this or point me to where this has already been done? Thanks.

EDITS:

Presently reading here: https://volvo850wagon.wordpress.com/cat ... g/coolant/

Found coolant testers. Assume that if you are measuring gases, you can measure at coolant reservoir.

Post by **scot850** » 30 Jun 2020, 15:02

You can use coolant gas testers to check for head gasket leaks and you may be able to borrow/rent a coolant system pressure tester. Be careful not to over pressurise the system as you can do more harm than good.

If the leaks are not obvious then the harder ones to notice are:

1) Any coolant pipe connector
2) Check the sides of the radiator for dampness, and particularly the top hose under just under it.
3) Lower coolant radiator pipe, especially around the back of the engine where hidden.
4) Water pump - may only leak when cold or when cooling down. Look for traces maybe immediately after starting or 30 minutes after switching off.
5) Cracks in the header tanks
6) Hose to rear of block from heater tank. Look for green around the hose joint to the metal pipe.
7) Turbo only - Turbo coolant pipes
8 ) Heater hoses and heater core 'O' ring seals - Look under carpet by gas peddle. Look carefully for tracer marks in dust under the carpet

I have had a similar issue this spring with my 'R' that there is evidence of coolant around the header tank pressure cap.

Neil.

Post by **wizechatmgr** » 30 Jun 2020, 17:43

What scot850 said - rent a tester so you can put the system under pressure if the exhaust gas test is a negative. Odds are you have a very slow drip.

How long ago did you do a cooling system refresh? Any hose over 10 years old should likely be replaced, if only for the fact it will be going soon at some point.

Post by **Eddystone** » 01 Jul 2020, 20:21

Bought a Lisle kit for checking for exhaust gases in the coolant. Tested the heck out of it, saw some vapor being pulled through the test fluid under vacuum, and the test solution stayed blue. So, I'm about as sure as I can be that there are no exhaust gases getting past the head gasket. That's on the 1998 V70 that I want to take on a trip. I have a couple of hoses and will make absolutely sure the heater core isn't the culprit tomorrow. Have a couple of hoses that I can install. May do the heater hose mod using the original fittings, if time allows.

That's on the 98 V70. I'm also looking at the 99 T5, but got caught by local rain.

Happy byproduct, when grabbing vacuum from the intake manifold, I found a split where the hose connects to the EVAP solenoid which may finally fix that recurring issue. These old Volvo hoses have a "string" of nylon or something that runs along one side of the hose, apparently to keep the hose from being stretched lengthwise. when the hoses get really old, the hoses split along that reinforcing filament, sometime the full length of the hose as on my T5 under the intake manifold. When they are just tired enough, they split at the end of the hose along that filament. Cheap to replace with generic hose, but they look okay until just before they go because they become thin where that filament runs. I guess we just have to routinely replace this stuff. In this specific situation, there was no big vacuum leak, but I actually heard a hissing sound. Engine idled fine with the hiss. Removing the hose caused a dramatic difference. I am suspecting (and I have been wrong before) that when the solenoid opened to do its EVAP thing, that system intermittently did not sense sufficient vacuum and would throw an error once in a while even if it was not a hard failure.

What would we do with ourselves if we didn't have P80s to fiddle with?

Post by **abscate** » 02 Jul 2020, 04:58

How much coolant use are we talking here? How often are you topping off?

Post by **Eddystone** » 02 Jul 2020, 14:57

abscate wrote: ↑02 Jul 2020, 04:58 How much coolant use are we talking here? How often are you topping off?

Hard to say in miles driven. Both cars constantly need to be topped up. Maybe an overflow tank every three days. Recently accelerated in both cars. Both read normal temps. Tank and caps don't seem to be leaking. Replaced caps anyway. Have done cores on both cars. Need to pull up carpets, but no smell or fog and were leak-free when installed. Did exhaust gas test on V70 and got no color change. Can't find any obvious leaks. Planning on replacing both upper and lower hose (upper already done on S70). Have 5/8" heater hose to reuse fittings. Can't get hold of new yellow clips immediately and not too sure about reusing old clips - though I can get new o-rings locally.

No obvious leakage anywhere, but the Zerex ZO5 coolant I'm using is basically clear and dries white, so not as obvious as green coolant. I have genuine blue Volvo coolant for use when I replace the hoses.

Cars are not overheating. Fan is working. Will check for exhaust gas in the T5 turbo tonight. The non-turbo V70 seems fine in terms of gases in the coolant.

Post by **Eddystone** » 02 Jul 2020, 14:59

abscate wrote: ↑02 Jul 2020, 04:58 How much coolant use are we talking here? How often are you topping off?

It's been 30 seconds since I posted my response. What's with the delay?

Post by **abscate** » 02 Jul 2020, 15:01

A lot of people, myself included, can’t smell coolant. Definitely pull up the carpets and look for pools

500 mL very three days is a lot of coolant. Those white traces can be the leaks.

The coolant exhaust test gives no false positives but does give false negatives

;(

Post by **abscate** » 02 Jul 2020, 15:01

Post by **Eddystone** » 02 Jul 2020, 16:55

abscate wrote: ↑02 Jul 2020, 15:01 A lot of people, myself included, can’t smell coolant. Definitely pull up the carpets and look for pools

500 mL very three days is a lot of coolant. Those white traces can be the leaks.

The coolant exhaust test gives no false positives but does give false negatives

;(

It does seem like a lot of coolant, and that's why I am surprised that I can't figure out where its going to. I think it must be leaking from low down and immediately vaporizing when it escapes. Right now, I am suspecting possibly the back end of the lower radiator hose, and will pull that area apart and replace that. I have one for each car. The white traces I've seen are from me releasing pressure and spraying drops. Just cleaned engine the other day, too. I will try the coolant test again on this car and then on the other car, as well. Vacuum is pulling through a bubble every couple of seconds when things are cooking, so I think I am getting sufficient stuff through the solution.

They run fine, but if I can't find the leak, I'll drive them both to Albany and dump them somewhere.