Overheated -Hard Starting

Faust · Post by **Faust** » 24 Jul 2020, 16:38

'04 V70 NA Last weekend I overheated. added coolant, went on my way. Car stalled at idle, but restarted. Got to a shopping center where I could let it cool off. Absolutely wouldn't start, called AAA (A real treat to comply with social distancing, I had to take a cab). Anyway short of time, I let it sit for two days. Started right up. Now it will "usually" start but not easily. Seems like a fuel problem. It will catch and if I jiggle the pedal it will catch then run roughly for a few seconds. In operation it runs perfectly. (I have tried ether, without result). Now I am back to no start, any suggestions?

Post by **jonesg** » 24 Jul 2020, 19:06

Faust wrote: ↑24 Jul 2020, 16:38 '04 V70 NA Last weekend I overheated. added coolant, went on my way. Car stalled at idle, but restarted. Got to a shopping center where I could let it cool off. Absolutely wouldn't start, called AAA (A real treat to comply with social distancing, I had to take a cab). Anyway short of time, I let it sit for two days. Started right up. Now it will "usually" start but not easily. Seems like a fuel problem. It will catch and if I jiggle the pedal it will catch then run roughly for a few seconds. In operation it runs perfectly. (I have tried ether, without result). Now I am back to no start, any suggestions?

if it was a fuel problem , wouldn't ether make it fire for a few seconds?

Back to the chain of events, why did it overheat?
low coolant?
why was it low on coolant?

Any codes? money light?
Any messages in the DIM ?

Injectors showing a pulse on a noid light?...or backprobe with a meter, I think its 5v.
same on the coils. Got spark?

If you have a test light you can quickly check the fuses in the engine bay without pulling them.
Get a computer safe probe. I got the $16 Lisle probe from autozone or O'Reiley.

Theres also a possibility the overheat damaged a sensor.
what does the tach do when the engine is cranking but not firing?
So ... need to gather some basic information.

Faust · Post by **Faust** » 24 Jul 2020, 19:46

if it was a fuel problem , wouldn't ether make it fire for a few seconds?
That was my thought. Couldn't find anyway to spray it directly, so I sprayed it on the air filter itself. Could have evaporated quickly.

Back to the chain of events, why did it overheat?
low coolant?
why was it low on coolant?
I had blown a head gasket. Tried head gasket sealer which worked well, but not completely. Very hot day and I had the A/C on. I think that caused the problem.

When it starts, it seems to run on fewer than all cylinders. In seconds it begins to fire on all and runs smoothly and quietly. No steam out the exhaust, or other usual signs of a head gasket. Maintains normal temperature just running around town.

Only message relates to brakes.

Post by **jonesg** » 24 Jul 2020, 21:12

ahh, thats it then, head gasket.
When engine is off the coolant is seeping into the cyl and drowning the plug.
Once it fires the cyl dries out and the combustion catches.
Whilst its running the combustion is over pressurizing the coolant.
When you shut it off the coolant is forced back into the cyl and so it goes.
I had the same problem in an earlier volvo.
When the engine is cold you may find the coolant bottle still under pressure.
Needs a gasket and head skim.

Post by **SuperHerman** » 25 Jul 2020, 00:10

Pull the spark plugs and look down the holes - you don't want to see clean cylinder tops as that will show signs of a failed head gasket. You can rent a tester (have to buy the fluid for it) from Autozone to test if you have combustion gases in your coolant.

The fact you are not getting smoke out the exhaust is what has my questioning head gasket failure, although it is possible.

If all the head gasket checks don't point to the head gasket - I would focus on all temperature sensors. A failing sensor could cause start and running issues.

Post by **abscate** » 25 Jul 2020, 04:59

Time for a compression test. You did well to get some life out of head gasket sealer, that usually fails.

Faust · Post by **Faust** » 25 Jul 2020, 07:49

SuperHerman wrote: ↑25 Jul 2020, 00:10 Pull the spark plugs and look down the holes - you don't want to see clean cylinder tops as that will show signs of a failed head gasket. You can rent a tester (have to buy the fluid for it) from Autozone to test if you have combustion gases in your coolant.

The fact you are not getting smoke out the exhaust is what has my questioning head gasket failure, although it is possible.

If all the head gasket checks don't point to the head gasket - I would focus on all temperature sensors. A failing sensor could cause start and running issues.

I suspected sensors, but can't figure which would be effected by heat. As I mentioned, I let it sit for a few days and it started right up. With use, that situation deteriorated.

Post by **jonesg** » 25 Jul 2020, 10:35

Most coolant goes out the overflow or coolant bottle cap, not through the combustion chamber.
Coolant system is 15 psi, engine cyls 140 psi, engine wins the pressure game.

If you have a spare coolant bottle cap, drill a hole in it and insert 2 feet of tubing, 1/4 inch is ok.
Run the tubing into a bottle filled with water.
Start engine and watch the bubbles, it will bubble a bit as the coolant pressurizes but watch what happens after 2 minutes when throttle is varied, if the bubble increase and decrease with throttle its exhaust gas coming through the coolant system.
I did this test and it was quite definitive. No question about it .

I wouldn't bother throwing sensors at it, everything already says head gasket.

At this point if you drive it you're playing coolant roulette.

Faust · Post by **Faust** » 25 Jul 2020, 11:51

I just noticed, after a AAA tow, that it has a radiator leak. It overheated and wouldn't start.

Post by **jonesg** » 25 Jul 2020, 21:04

Faust wrote: ↑25 Jul 2020, 11:51 I just noticed, after a AAA tow, that it has a radiator leak. It overheated and wouldn't start.

I haven't done it myself but the gasket job doesn't look too difficult.
Getting the head skimmed isn't too expensive.