1998 V70 N/A Cooling Mystery

[kanona40]

I bought a 1998 Volvo V70 N/A, 6 months ago with the heater core bi-passed.

A month ago I decided to tackle the problem. A list (all new except the radiator) of what I replaced:

1) Water Pump (as part of a complete timing belt job)
2) Thermostat (87C) and seal.
3) Temp switch for cooling fans, and connector housings with internals. (thermo-switch)
4) The two heater core hoses.
5) The rear hard pipe to water pump oring.
6) The Coolant Reservoir, and cap (150kpa/21psi)
7) All coolant hoses, and clamps (stainless).
8) The firewall heater hose junction coupler, hard pipes, and silicone orings for heater core.
9) Heater core.
10) Spare radiator from former running parts car.
11) Radiator mounts.
12) 2 speed relay for cooling fan.

Flushed the system.

I connected my garden hose to the reservoir bottle with adapter (for pressure), opened the drain cock on radiator, with thermostat removed and oring to seal, filled the system and ran the car for an hour+.
While car was running, warm, and on jack stands (similar to open system on a marine engine), I started running my laser temp on the flow. My average temps like this was 145F-150F.

Then I dumped the hose water. With the drain cock closed, thermostat re-installed, filled the system with distilled water. While engine running, opened drain cock, and refilled the reservoir with distilled water till hose water was cycled out.

I drained the system, then closed the drain cock. I attached my motive brake bleed (cleaned) and put the system under 15psi for 30 minutes. 0 pressure loss.

I filled the system with 50/50 mix distilled water and Volvo blue. I ran a fan cycle and let it cool. I put a little more coolant in the reservoir and let it run. It ran 4 cycles fine, then the coolant rushed in to the reservoir and the cap released the overflow. The fan kicked on and the coolant lowered in the reservoir.

I observed proper level on the temp gauge and the thermostat housing was at 191F as well when I shot the temp.

I shut the engine off and let it cool completely.

The next morning I pulled the spark plugs. No overheat, oil, excess carbon, or white from coolant.
I took out the thermostat and coolant came out and I put the thermostat in a pot on the oven and watched the thermostat open and close like it should.

I re-installed the thermostat, spark plugs, and refilled with some coolant. I started the engine and after one successful fan cycle turned the engine off.

I ran a dry and wet compression test with remote starter and throttle body valve clamped open.

The dry test:

1) 225 psi
2) 218 psi
3) 235 psi
4) 210 psi
5) 220 psi

Wet test :

1) 248 psi
2) 255 psi
3) 271 psi
4) 266 psi
5) 268 psi

Then I ran a leak down with an OTC tester at 90 PSI of pressure for these results:

1) 86% (4% leak)
2) 87% (3% leak)
3) 88% (2% leak)
4) 86% (4% leak)
5) 74% (17% leak)

(#5 results concern me. perhaps a crack above a valve seat in the head?)

I then buttoned it all up and started the engine with the cap off and looked for bubbles. None.

Next, I used a block tester. The fluid stayed blue.

I have no exhaust smoke (white). I don’t have moisture in the oil.

My plan next is to remove the radiator and remove the end tanks to rule it out. After this, I can only think of removing the head.

Have I missed something in this?

[misha]

You shouldn't drain the coolant with engine running,never.When you replace the coolant you ALWAYS run the engine with expansion cap REMOVED untill the fan cycles.

After reading your post i don't see what is wrong with the car.

If you are concern about compression results,there is nothing to be worry about,yet.Car probably have high mileage and some wear internally is expected.Some wear from valve seals plus some wear from piston rings and you got what you got.If the engine is running strong and don't have high oil consumption like visible blue smoke from exhaust..i wouldn't worry about it.

[precopster]

As problems began more or less once a thermostat was fitted have you gone back to no thermostat for another test.

What brand are:

1) temp switch
2) thermostat
3) 2 speed relay

As these 3 items closely determine coolant temperature they should be OEM. The temp switch may be out of range and can be tested in a pot of water. Here's a table of correct values for the temp switch

0 degrees - 5740 Ohms
10 degrees - 3700 Ohms
20 degrees - 2450 Ohms
40 degrees - 1150 Ohms
80 degrees - 318 Ohms
100 degrees- 184 Ohms

[precopster]

If you're worried about the coolant rush into the reservoir just do at least 4 warm up and cool down cycles and top up after each one to ensure correct coolant level.

Those numbers mean pretty much nothing on an old engine.

[misha]

0 degrees - 5740 Ohms
10 degrees - 3700 Ohms
20 degrees - 2450 Ohms
40 degrees - 1150 Ohms
80 degrees - 318 Ohms
100 degrees- 184 Ohms

It should be around these values,but some minor variance is accepted.

[kanona40]

misha,precopster, thank you for your timely reply.

The motor has 121,000 miles on it.

The problem is in the pressure build. After enough (possible) heat soak? The cap will release coolant. I can measure this build up of pressure when I put my gauge on the reservoir. The coolant can be observed after about 4 fan cycles moving in the bottle from the bottom mostly until it fills the bottle to overflow (cap release of pressure).

I was hoping to have bad numbers on my compression test, no such luck (crazy I know, just wanted something concrete). On the leak down still nothing very telling.

precopster,

1) Wahler 87C #271417
2) ECT Volvo OE #114142
3) KAE (IPD#106595) #1398845

Thank you for the specs, I will put it on the stove and find out.

On your other post;

I have and the problem persists, I should be able to leave the engine idle in the FL sun at 80F outside temp for hours without issue

I will go and get those temp values, report back, and if all is good and with an inside visual of the radiator is good then I guess it is time for Head Gasket job, mainly for inspection.

[kanona40]

My original assessment with the car when I bought it, was that the prior owner had used stop leak and since he had the green glycol in it with a bi-pass on the heater core that it was all junked up inside with possible water jacket clogs or blown head gasket.

This is why I just replaced everything in the system, spent so much time flushing and I had my evidence when I pulled out both the old radiator and the heater core. The heater core was blown out of the top with the solidified stop leak in clumps. The radiator was clogged so bad I could rattle the clumps out.

[misha]

What pressure?

There should be some pressure in expansion tank untill thermostat opens...every time.That's why it have a cap with specific pressure relief.

From your descrption,same things would happen in expansion tank if it's overfilled.

[kanona40]

at 82F infrared temp The ECT is 1731 ohms, if tis is incorrect, then I have received the wrong part, this would make sense of it all, I will pull the part and read the numbers.

[kanona40]

28 C (82F) I figure according to the above scale is approx 1930 ohms and 200 ohms off from the scale is not bad if its relative. I have confirmed that the ECT is the right one.

I'm in FL so for those of us in the States:

10 C = 50 F--3700 ohms
20 C = 68 F--2400 ohms
40 C = 104 F-1150 ohms
80 C = 176 F-318 ohms
100 C = 212 F-184 ohms

is the fan tripped at 184 ohms (or what temp)? or less?