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['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Help, Advice and DIY Tutorials on Volvo's extremely popular car line -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

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SvenGWK
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['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by SvenGWK » Thu Mar 29, 2018 9:24 am

Now that I have gotten myself everything in order to get the car fit again, I have once again taken a closer look at the "old" problem of the vehicle.
The car's been losing small amounts of coolant ever since I got it. Since the vehicle sometimes smells of coolant or its steam during fast journeys, I always suspected a slightly leaking hose to the heat exchanger or a slightly leaking heat exchanger.
The coolant level drops when the engine is warm and normalizes when the tank is opened. If I only drive in the city I have to refill about 300ml every 6-8 weeks.
The loss is quite constant, I drove about 15000 km with the car.

The old green cap of the expansion reservoir had cracks all around, I have already replaced it.
I haven't noticed puddles or wet spots so far, the carpet on the passenger side is dry.
The water is definitely getting gaseous, I just don't know where yet.

The car barely smokes in idle, when accelerating there are just bright exhaust gases, but they don't look unusual to me.
No oil seems to float in the cooling water, nor can I see any mud on the oil cap or dipstick.
No backfires, vehicle starts great.

I want to do a CO2 test on the coolant tank at the weekend, got some test liquid and a suitable cap.
I also bought a test kit for the engine oil, it should be possible to detect traces of antifreeze in the oil quite well with it.

Today I did the test on ascending bubbles, which is often shown on YouTube.
There are no bubbles in the expansion tank when the engine is cold.
When the engine has warmed up a little (needle at 1/4) and the water runs out of the thin hose into the expansion tank,
some small bubbles appear in this corner at increased revolutions (at surface). Looks to me like those bubbles are coming out of that thin tube.
The thermostat is obviously working and the engine is never overheated. (I don't remember the needle ever going far beyond the middle.)
The OBD measurement also shows temperatures in the range 65-103°C (149-218F) only. Above 100°C only at full load.


Is this normal in this case or do these small bubbles already indicate a major problem?
Does it speak for a crack in the cylinder head or block if the loss of coolant is constant over a longer period of time or could it also be "just" the head gasket?

Could there be other causes?
I had read e.g. that with old hoses and small leaks in the system no proper pressure can build up and thus the water evaporates.
The resulting steam then collects in the expansion tank and presses the water into the old soft hoses up to 1.5 bar, the rest goes out through the cap valve.

In fact, I occasionally have small amounts of coolant in the edge of the tank under the screw cap.
It may be possible, of course, that in the tank at full throttle and warm engine instead of small bubbles all hell breaks loose - but I can't see that while driving... ^^



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WhatAmIDoing
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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by WhatAmIDoing » Thu Mar 29, 2018 9:40 am

If you had a cracked block, it would be pretty obvious. At least one cylinder would have no compression. IMHO, this does not scream head gasket leak based on what you described. Based on the condition of the cap, I would suggest replacing all the radiator cooling hoses. Check the turbo for coolant leaks. The coolant tank may also deserve replacing. Definitely pull the bolster panels off and check the heater core. Mine was leaking but did not present any obvious symptoms. If you don't see coolant spots, place some white paper or paper towels under the heater core and drive around for a few days. If you find spots, replace the core.
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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by SvenGWK » Thu Mar 29, 2018 11:03 am

I just removed the driver's side bolster panel. Doesn't look like there's any leaks. All dusty. I will try this with the paper, maybe something will show up when the car is really warm.



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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by WhatAmIDoing » Thu Mar 29, 2018 11:50 am

You are going to have to get the car warmed up and drive around to make any leaks known. I left the cover off and white paper towels down under the core for about a week. Saw green spots from coolant, changed the core (really easy), all is well now. This stopped my coolant leak until the lower rad hose started leaking.


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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by scot850 » Thu Mar 29, 2018 12:21 pm

For mystery leaks the favorites for me are on turbo engines (and where appropriate for non-turbos):

1) 'O' ring seals for the heater core. Does the windshield feel greasy above the air vents?
2) The heater core itself? A small leak may just evaporate, but you may smell a sickly sweet smell when driving.
3) The heater hoses and the joint at the bulkhead and the hoses to the engine.
4) The radiator. Check for discoloration particularly on the passenger end around the joins between the end of the radiator and the center core.
5) Turbo only - Check the 2 coolant hoses to/from the turbo for swelling and leaking
6) Check for leaks from the coolant tank (they crack with age)
7) Check for tell-tale water marks from the coolant reservoir cap
8) Check under the car when starting from cold for leaks at the timing belt end. Could be the water pump seal going. Once warm the pump can seal again and then leak again when it cools. Put paper under there or cardboard to see if it gets damp.

Neil.
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SvenGWK


2000 V70 R - still being an endless PITA
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2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
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1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by SvenGWK » Thu Mar 29, 2018 1:15 pm

1) No, I don't think so. I don't have any problems with fogged windows either.
2) Yeah, I actually had that smell in my nose a couple of times when I was driving.
6) Everything's dry there.
7) Occasionally I discover some coolant under the edge of the lid. Since I have already replaced the cap, I assume it works normally and only let some pressure out under high engine load.
A pressure builds up in the system, visible by the fact that the coolant level drops when the engine is hot.

Thank you for this checklist! I will examine the other points very carefully.
There are obviously a few more ways to lose coolant than a major engine damage...
Anyway, I hope the CO2 test gives me clarity about the head gasket.
Is there an explanation for these bubbles in the coolant tank?



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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by abscate » Thu Mar 29, 2018 2:01 pm

7) Check for tell-tale water marks from the coolant reservoir cap
8) Check under the car when starting from cold for leaks at the timing belt end. Could be the water pump seal going. Once warm the pump can seal again and then leak again when it cools. Put paper under there or cardboard to see if it gets damp.
Ha! Thats the forum equivalent of tp on the shoe..

:lol: :lol: :lol:


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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by SvenGWK » Wed Apr 04, 2018 11:10 am

I drove about 500km this weekend.
On the outbound trip I had a loss of about 250ml of coolant, I refilled it.

By the way:
I did a CO2 test on the coolant tank immediately after the trip - negative.
I did an oil test - no water in the oil.
No oil floats in the cooling water.

Since my lambda sensor had said goodbye again at 180km/h, I wanted to replace it. However - a workshop has to do that now. I have not been able to remove it and the hexagon is now something..... you know.
Luckily, the sensor worked again, so I didn't drive very fast on the way home. What can I say - the car hasn't used a drop of coolant since it was refilled!
I have noticed, however, that my thermostat is not working properly. At the moment it seems to be stuck in a "permanently open" state. My engine has been struggling to exceed 70°C at higher speeds.
I'm afraid it may have jammed in another position before, because the engine always warmed up quite quickly. I think the temperature gauge does not really give a clear picture of the temperature, the needle is centered at 90°C and not much higher at over 100°C. I assume therefore the overpressure which was regularly present in the tank and my cooling water "pressed down" came about by evaporated water.
I'll replace the thermostat tomorrow, but I'm afraid the engine has already been damaged.
I won't really find out until I have installed the new lambda sensor and can drive again over a longer distance at a little more speed.
If it then again drinks water there is probably something broken.
If something were leaking in the heating system or radiator, water would disappear even when driving slower.

This is my car after the cold start at a temperature of about 6°C. When the engine is warm, there is no more smoke.
Most people say it's all perfectly normal and I'm chasing ghosts.
http://sendvid.com/iellet2j



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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by scot850 » Wed Apr 04, 2018 11:39 am

That is perfectly normal. If the car does a lot of short trips and few at highway speed they tend to get a build up of condensation in the exhaust system which only burns off after a good long run.

Your car is normal in terms of the amount of moisture/smoke you are seeing.

If your thermostat has failed, if it is a good one they fail open as your car has not overheated. Replace with a good quality one like and OE Volvo or Wahler. Over here they open at 90C, some markets open at 87C.

Neil.


2000 V70 R - still being an endless PITA
2006 XC70
2003 Toyota 4Runner V8 Limited
2015 Kia Sportage EX-L
1993 850 GLT -Sold
1998 V70 XC - Sold
1997 Volvo 850 SE NA - Went to niece in California - Sold
2000 V70 SE NA - New project and test bed - Sold

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Re: ['98 C70 B5254T] blown head gasket, cracked block or s.th. completely else?

Post by SvenGWK » Wed Apr 04, 2018 12:51 pm

Thank you, that gives me hope.
I will replace the thermostat and try if this pressure phenomenon comes back or if water disappears again.
Would be nice if the solution were that simple...



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