For those of us who understand psi better than bar...
http://www.lenntech.com/unit-conversion ... essure.htm
1.3 bar is just under 19 psi.
Coolant pressure to high
-
stoutlogic
- Posts: 182
- Joined: 3 January 2006
- Year and Model: 2006 XC70
- Location: NJ
- Been thanked: 4 times
I wouldn't go pulling the head as of yet. Its a lot bigger job then you may wish for. If you had a bad head gasket you would be blowing white smoke out the tailpipe, car would idle poorly and the cylinders with the leaks would be spotless as would the spark plug. Coolant leaks clean the hell out of the tops of pistons, all carbon would be gone.
1.)Are you sure there is too much pressure? The hoses should be firm / hard when the coolant is hot.
How about starting with a pressure guage on top of the expansion tank?
2.) You may have too much coolant in the system. System only holds so much. Read # 3 below. If you have a clog and keep adding more coolant same result will follow.
3.) You may have a blockage in the bottom of the expansion tank, return hose to the thermostat housing or in the thermostat housing itself. The orfice in the thermostat housing is fairly tiny. Any loose contamination
could clog the return path from the expansion tank to the housing.
Does the coolant overflow while driving? How about if you leave the car running and pop the hood?
If it only overflows when you shut down the car my guess is some sort of blockage between expansion tank and thermo housing. Coolant has no were to go but thru the top of the cap since it cant make it back into the system.
4.) Bad expansion tank cap. should be a cheap/ easy fix. Double check to make sure the hose coming from the tank back to the top of the theromstat housing is clear.
What about the hose at the bottom of the radiator? Is it rock hard as well when hot.?
The coolant passages in the head and block are fairly large I doubt your problem lies inside.
1.)Are you sure there is too much pressure? The hoses should be firm / hard when the coolant is hot.
How about starting with a pressure guage on top of the expansion tank?
2.) You may have too much coolant in the system. System only holds so much. Read # 3 below. If you have a clog and keep adding more coolant same result will follow.
3.) You may have a blockage in the bottom of the expansion tank, return hose to the thermostat housing or in the thermostat housing itself. The orfice in the thermostat housing is fairly tiny. Any loose contamination
could clog the return path from the expansion tank to the housing.
Does the coolant overflow while driving? How about if you leave the car running and pop the hood?
If it only overflows when you shut down the car my guess is some sort of blockage between expansion tank and thermo housing. Coolant has no were to go but thru the top of the cap since it cant make it back into the system.
4.) Bad expansion tank cap. should be a cheap/ easy fix. Double check to make sure the hose coming from the tank back to the top of the theromstat housing is clear.
What about the hose at the bottom of the radiator? Is it rock hard as well when hot.?
The coolant passages in the head and block are fairly large I doubt your problem lies inside.
Thank you for you insight Stoutlogic.
I'm sure there is too much pressure on the system, for a few weeks i lost some coolant after shutting of the engine but i though it was a bad expansion cap so just topped it up every now and then. But i was cruising on the highway at a steady 80mph for about an hour when suddenly the brakes felt odd. So i pulled over and coolant had come out of the reservoir and dripped down over the right front brake. The hoses were rockhard and the fan was spinning at max speed. I let it idle for a while but it just got worse, so i let some water out (carefully) to release some pressure and after that it overheated. I shut it off and let it cool down for a while. Its been like that ever since.
All the hoses get rockhard everywhere and none of them seem blocked, also when the engine is warm and you rev it the water streams from the thermostathousing (little hose) to the reservoir.
I tried putting less coolant in the system and this helps to keep the pressure down for a while, but drive it for a bit and the same problem occurs.
Having replaced pretty much the whole cooling system i don't think the problem lies there. I've seen many (lesser
) cars with blown headgaskets and none of them were nearly as subtle as this. But its the only option i can think of anymore. Weird thing is, it runs and starts fine and doesn't seem to consume coolant like you would expect. I suppose the headgasket leak is so small that only cilinder exhaust goes through it but not coolant, even after shutting it off or pressure testing it.
I'm sure there is too much pressure on the system, for a few weeks i lost some coolant after shutting of the engine but i though it was a bad expansion cap so just topped it up every now and then. But i was cruising on the highway at a steady 80mph for about an hour when suddenly the brakes felt odd. So i pulled over and coolant had come out of the reservoir and dripped down over the right front brake. The hoses were rockhard and the fan was spinning at max speed. I let it idle for a while but it just got worse, so i let some water out (carefully) to release some pressure and after that it overheated. I shut it off and let it cool down for a while. Its been like that ever since.
All the hoses get rockhard everywhere and none of them seem blocked, also when the engine is warm and you rev it the water streams from the thermostathousing (little hose) to the reservoir.
I tried putting less coolant in the system and this helps to keep the pressure down for a while, but drive it for a bit and the same problem occurs.
Having replaced pretty much the whole cooling system i don't think the problem lies there. I've seen many (lesser
) cars with blown headgaskets and none of them were nearly as subtle as this. But its the only option i can think of anymore. Weird thing is, it runs and starts fine and doesn't seem to consume coolant like you would expect. I suppose the headgasket leak is so small that only cilinder exhaust goes through it but not coolant, even after shutting it off or pressure testing it.'98 V702.5Turbo silver auto VSI aircon ice
'89 480Turbo Graphite Grey ecu-mod aircon
'89 480Turbo Graphite Grey ecu-mod aircon
-
stoutlogic
- Posts: 182
- Joined: 3 January 2006
- Year and Model: 2006 XC70
- Location: NJ
- Been thanked: 4 times
We have to clear the cobwebs and start fresh. The cooling system isn't rocket science. Got to be able to find the root of this problem.
Q1.) Is the car overheating while driving? Is the ID10T light coming on?
Q2.) What is the coolant temp reading? My 98 v70 t5 always reads 3 o'clock position when at operating temp.
Again if you had a bad head gasket the pressure from the coolant, especially if it was excessive, would drive the coolant into the cylinders not necessarly the other way around. Plus you state the car runs well. You haven't found oil in you coolant, have you?
Q3.) How does your oil look? Any milky white stuff, evidence of coolant in oil?
I would tend to think if by some remote chance the head gasket was the culprit leaving the expansion cap off while driving would remedy the pressure problem. Any combustion that left the cylinder would creep out thru the open expansion tank
This is my block with the head removed, you can see the cylinders are surrounded by the coolant jacket
Q1.) Is the car overheating while driving? Is the ID10T light coming on?
Q2.) What is the coolant temp reading? My 98 v70 t5 always reads 3 o'clock position when at operating temp.
Again if you had a bad head gasket the pressure from the coolant, especially if it was excessive, would drive the coolant into the cylinders not necessarly the other way around. Plus you state the car runs well. You haven't found oil in you coolant, have you?
Q3.) How does your oil look? Any milky white stuff, evidence of coolant in oil?
I would tend to think if by some remote chance the head gasket was the culprit leaving the expansion cap off while driving would remedy the pressure problem. Any combustion that left the cylinder would creep out thru the open expansion tank
This is my block with the head removed, you can see the cylinders are surrounded by the coolant jacket
Ok starting over 
a1: The car does not seem to be overheating, no idiot light
a2: Coolant temp gauge is always at 3 O'clock when at operating temp.
a3: There is no oil in the coolant or visa versa. Oil looks perfectly clean like it always does, the last oil change was about 4000miles ago. No mayonaise anywhere.
If i was to leave the expansion cap of while driving (or idling) coolant would continue to pour out of the expansion tank until there wasn't enough in the system. I've tried this. But if you switch the engine off and let it cool down the coolant level drops to nothing in the expansion tank. The thing that i don't understand is that it only starts to build pressure when the engine is hot.
a1: The car does not seem to be overheating, no idiot light
a2: Coolant temp gauge is always at 3 O'clock when at operating temp.
a3: There is no oil in the coolant or visa versa. Oil looks perfectly clean like it always does, the last oil change was about 4000miles ago. No mayonaise anywhere.
If i was to leave the expansion cap of while driving (or idling) coolant would continue to pour out of the expansion tank until there wasn't enough in the system. I've tried this. But if you switch the engine off and let it cool down the coolant level drops to nothing in the expansion tank. The thing that i don't understand is that it only starts to build pressure when the engine is hot.
'98 V702.5Turbo silver auto VSI aircon ice
'89 480Turbo Graphite Grey ecu-mod aircon
'89 480Turbo Graphite Grey ecu-mod aircon
-
stoutlogic
- Posts: 182
- Joined: 3 January 2006
- Year and Model: 2006 XC70
- Location: NJ
- Been thanked: 4 times
That's the way it should work. You shouldn't have any pressure untill the coolant in the block heats up, the thermostat opens and the coolant flows thru the entire system.Bramdeman wrote:Ok starting over
a1: The car does not seem to be overheating, no idiot light
This is good. Coolant is flowing thru block and rad.
a2: Coolant temp gauge is always at 3 O'clock when at operating temp.
Very good, coolant is staying within range, rad is working
a3: There is no oil in the coolant or visa versa. Oil looks perfectly clean like it always does, the last oil change was about 4000miles ago. No mayonaise anywhere.
Good
If i was to leave the expansion cap of while driving (or idling) coolant would continue to pour out of the expansion tank until there wasn't enough in the system. I've tried this. But if you switch the engine off and let it cool down the coolant level drops to nothing in the expansion tank. The thing that i don't understand is that it only starts to build pressure when the engine is hot.
Wonder if you have air trapped inside the system?
Did you try a new expansion cap yet? I didn't see it any your previous posts.
-
MadeInJapan
- MVS Moderator
- Posts: 13434
- Joined: 31 March 2005
- Year and Model: '98 S70 T5 '07S40T5
- Location: Knoxville, TN American but born in Japan
- Has thanked: 17 times
- Been thanked: 35 times
Right...expansion tank caps are a known problem area. I carry one in my glove box as a spare. In our old 850 I went through at least one every year...even the new green ones which were redesigned and are suppose to be better.
'98 S70 T5 Emrld Grn Met/Beige Tons of Upgrades Mobil-1
'04 V70 2.5T Red/Taupe Some Upgrades Mobil-1
'07 S40 T5 AWD 6 speed manual! Silver/Black Stage1 Heico & Elevate
'07 S60 2.5T Blue/Taupe- my kid's Volvo
'04 V70 2.5T Red/Taupe Some Upgrades Mobil-1
'07 S40 T5 AWD 6 speed manual! Silver/Black Stage1 Heico & Elevate
'07 S60 2.5T Blue/Taupe- my kid's Volvo
I finally got around to taking the head off and it turns out it was the head gasket after all. From the looks of it it was leaking from the tiny little waterchannels that run inbetween the cilinders. It wasn't nearly as bad too do as i had feared, it took about 8 hours of work in total. kindoff a weird setup for the camshafts in these engines but it runs so i guess we got it right
I didn't have the head skimmed becouse volvo told me not too and they only supply 1 thickness in headgasket. So i had it pressure tested and it came out fine. It never really overheated so figured it would be ok.
I think i know why it failed too, when the gasket came off you could see that someone had cleaned the engineblock with sandpaper before. So its not the first time the head came off.
I took some pictures while i was waiting for the head to come back from the shop. You can clearly see that the problem was in Cilinder 2 and that it was a very small failure. Also in picture 2 you can see (if u look closely) that somebody has worked on it before from the little scratches in the block.
Anyway i hope this info is of some use to somebody and many thanks for all the suggestions.
Bram
I didn't have the head skimmed becouse volvo told me not too and they only supply 1 thickness in headgasket. So i had it pressure tested and it came out fine. It never really overheated so figured it would be ok.
I think i know why it failed too, when the gasket came off you could see that someone had cleaned the engineblock with sandpaper before. So its not the first time the head came off.
I took some pictures while i was waiting for the head to come back from the shop. You can clearly see that the problem was in Cilinder 2 and that it was a very small failure. Also in picture 2 you can see (if u look closely) that somebody has worked on it before from the little scratches in the block.
Anyway i hope this info is of some use to somebody and many thanks for all the suggestions.
Bram
'98 V702.5Turbo silver auto VSI aircon ice
'89 480Turbo Graphite Grey ecu-mod aircon
'89 480Turbo Graphite Grey ecu-mod aircon
-
stoutlogic
- Posts: 182
- Joined: 3 January 2006
- Year and Model: 2006 XC70
- Location: NJ
- Been thanked: 4 times
I hope for your sake you are correct.
From the pictures its a little hard to tell but in general if the head is leaking you get contamination, ie coolant into cylinder, which sends white smoke out the tailpipe.
In addition the biggest tell tail is the leaking cylinders are spotlessly clean as the coolant de-carbonizes the top of the piston. I don't see that to be the case in your pics.
I guess if you had a bizarre one way leak you could be correct, but why didn't it show up in the coolant test?
I'll keep my fingers crossed for you.
From the pictures its a little hard to tell but in general if the head is leaking you get contamination, ie coolant into cylinder, which sends white smoke out the tailpipe.
In addition the biggest tell tail is the leaking cylinders are spotlessly clean as the coolant de-carbonizes the top of the piston. I don't see that to be the case in your pics.
I guess if you had a bizarre one way leak you could be correct, but why didn't it show up in the coolant test?
I'll keep my fingers crossed for you.
#2 cilinder is a lot cleaner than the rest of them but indeed not as clean as you would expect it too be, the only explanation i've got is that its a very small leak indeed.
I didn't take any pictures of the inside of the head but #2 was a lot cleaner than the rest, more so than the other cilinders.
Anyway it doesn't build pressure anymore.
I didn't take any pictures of the inside of the head but #2 was a lot cleaner than the rest, more so than the other cilinders.
Anyway it doesn't build pressure anymore.
'98 V702.5Turbo silver auto VSI aircon ice
'89 480Turbo Graphite Grey ecu-mod aircon
'89 480Turbo Graphite Grey ecu-mod aircon
-
- Similar Topics
- Replies
- Views
- Last post