Blowing my stack...and so is my 1985 V6
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  1. #1
    Tadpole
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    Default Blowing my stack...and so is my 1985 V6

    Wonder if anyone can help with a V^ that's building up so much pressure it not only blows hoses but a new radiator as well!!!
    For some background, the V6 is in a 760, which has a very small head gasket leak (block tester took 20 mins to discolour) new radiator, thermostat new and bored, 150kp expansion tank cap (slightly opened to bleed pressure but not enough to allow boiling), and there is NO evidence of water in the oil.
    It certainly runs quite hot, and I suspect from research that corrosion is the culprit.....but where?
    And is it worth fixing?
    I know Volvo don't reco the motors anymore, and that no-one else will either, as finding a good one to fix is nigh impossible.
    I've evn looked at swapping a seconhand 740 motor in, but I'm getting aome pretty heavy quotes to do it.
    Does anyone have a suggestion that doesn't involve shooting it?

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    PS...the rest of the car is in great shape, which is why I'm looking for solutions.

  2. #2
    Fellow Frogger! tasgill's Avatar
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    Howdy,

    If the water pump is driven by the fan belt, disconnect the belt, top up the radiator to the filler neck, get somebody in the car to start it while you watch, and if the water level moves at all as the engine starts, you have compression leaking into the coolant. It doesnt have to be the head gaskets, a cracked liner, head porosity, could also do it, and Im sure there are other possibilities.

    Terry

  3. #3
    1000+ Posts Wildebeest's Avatar
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    Icon14 Blowing my stack...

    Quote Originally Posted by Vision Hawk
    Wonder if anyone can help with a V^ that's building up so much pressure it not only blows hoses but a new radiator as well!!!
    For some background, the V6 is in a 760, which has a very small head gasket leak (block tester took 20 mins to discolour) new radiator, thermostat new and bored, 150kp expansion tank cap (slightly opened to bleed pressure but not enough to allow boiling), and there is NO evidence of water in the oil.
    It certainly runs quite hot, and I suspect from research that corrosion is the culprit.....but where?
    And is it worth fixing?
    I know Volvo don't reco the motors anymore, and that no-one else will either, as finding a good one to fix is nigh impossible.
    I've evn looked at swapping a seconhand 740 motor in, but I'm getting aome pretty heavy quotes to do it.
    Does anyone have a suggestion that doesn't involve shooting it?

    PS...the rest of the car is in great shape, which is why I'm looking for solutions.
    Ah.This takes me back to my Volvo days. Almost a regular service check item.
    We used a simple test. With engine running remove pressure cap carefully.
    Using the workshop CO meter, hold the end of the hose over [not in!] the coolant bottle, observe the co meter. If you see a reading you have a head gasket problem. The compression pressure pushing out the coolant. This will not show water in oil. That's another problem
    Do youself and your mechanic a favour and fit a B23 or B230 E four cylinder along with a five speed manual. Most Volvo mechanics advised this to unfortunate 264 and 760 owners.

  4. #4
    Budding Architect ???? pugrambo's Avatar
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    now then there is nothing wrong with a good PRV6 engine

    i'd day it is as simple as a head gasket IF you have been doing regular coolant changes

    also if there is corrosion get rid of the brass drain taps as they create electrolosis

    never seen a corroded 604 engine but have seen many a volvo one and this is the only difference on the block

    i would bet on a head gasket blown between a cylinder and coolant jacket

    if you keep running the car you will wake up one morning with coolant in at least one cylinder and my bet it will be the LH head

    why i don't know but more than 1/2 the head gaskets blow on the LH side
    3 x '78 604 SL

    1 x '98 306 GTi6

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0


    WTD long range fuel tank for 605

  5. #5
    1000+ Posts Wildebeest's Avatar
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    Default Blowing mmy stack etc

    Quote Originally Posted by pugrambo
    now then there is nothing wrong with a good PRV6 engine

    i'd day it is as simple as a head gasket IF you have been doing regular coolant changes

    also if there is corrosion get rid of the brass drain taps as they create electrolosis

    never seen a corroded 604 engine but have seen many a volvo one and this is the only difference on the block

    i would bet on a head gasket blown between a cylinder and coolant jacket

    if you keep running the car you will wake up one morning with coolant in at least one cylinder and my bet it will be the LH head

    why i don't know but more than 1/2 the head gaskets blow on the LH side
    "IF". Wasn't that a Rudyard Kipling poem that read something about..
    "If all those about you are losing their heads .." etc ?
    If you have any block corrosion, keep the brass drain cocks for they will be the only item of value left!
    Deja vu. Brass drain cocks / corrosion. Haven't we been here before?

    I would also wish no more than a head gasket problem for our 760 0wner.
    The suggested engine swaps were for those 260/760 owners who are left with terminal decay.

    I don't know if Peugeot's V6 factory bulletins were identical to Volvo but directions re head gasket replacement were updated all the time regarding tightening procedures. Lots of angle tightening here!!

    PS. Or was it.."If you can keep your head while those about you are losing theirs ?"
    Last edited by Wildebeest; 5th December 2004 at 11:33 AM. Reason: Add text.

  6. #6
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    Sounds like you have an oil leak into the cooling system, as this will build up very high pressure in the cooling system, enough to split the seams of a radiator.

    Usual culprit is porosity due to corrosion within the head. Note I don't have experience with your engine, but a 200B we had developed that problem (they were pretty notorious for corrosion within the head and the water outlets/inlets area) and it never had any signs of water in the oil sump, but there was an oily froth in the radiator!.

    In the case of the 200B a replacement head and some of the costliest new gaskets (then) fixed the problem along with careful attention to top level anti corrosion fluid in the cooling system.

    Good luck and yes I would remove any source of electolysis from dissimilar metals within the cooling system of any replacement engine.

    Ken

  7. #7
    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by Wildebeest
    "IF". Wasn't that a Rudyard Kipling poem that read something about..
    "If all those about you are losing their heads .." etc ?
    If you have any block corrosion, keep the brass drain cocks for they will be the only item of value left!
    Deja vu. Brass drain cocks / corrosion. Haven't we been here before?

    I would also wish no more than a head gasket problem for our 760 0wner.
    The suggested engine swaps were for those 260/760 owners who are left with terminal decay.

    I don't know if Peugeot's V6 factory bulletins were identical to Volvo but directions re head gasket replacement were updated all the time regarding tightening procedures. Lots of angle tightening here!!

    PS. Or was it.."If you can keep your head while those about you are losing theirs ?"

    mind you i have a pair of 604 heads here that are on a car that were cleaned up before refitting them that had done 400k and there was not an ounce of corrosion in them

    even the welsch plugs when pulled out to put new ones in weren't attacked by the corrosion disease

    but i do have a volvo block here and it's heads that are corroded

    the heads are savagable but the block i'm afraid will either take a lot of work or it will be converted into a coffee table
    3 x '78 604 SL

    1 x '98 306 GTi6

    1 x secret project

    1 x '98 406 STDT troop carrier and i don't care if it stinks, i don't sniff it's arse Death by wank tank

    1 x '99 406SV 5spd wagon, time to burn more fuel

    1 x 1994 605 SV3.0


    WTD long range fuel tank for 605

  8. #8
    Gone Fishin' Ray Bell's Avatar
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    It is true that the V6 in the Volvo seems to just rot away... but could it also be the radiator?

  9. #9
    Tadpole
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    Thank you very much to all those who have shared their expertise!!

    A few further bits of info are:

    1) On 2 occasions I have noticed a slight oiliness in the expansion tank. I presume from your comments that oil is getting into the coolant.

    2) Is there some way to distinguish between head corrosion or block corrosion, without pulling everything apart?

    Thanks,
    Michael

  10. #10
    1000+ Posts Wildebeest's Avatar
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    Default Blowing my stack etc

    Quote Originally Posted by Vision Hawk
    Thank you very much to all those who have shared their expertise!!

    A few further bits of info are:

    1) On 2 occasions I have noticed a slight oiliness in the expansion tank. I presume from your comments that oil is getting into the coolant.

    2) Is there some way to distinguish between head corrosion or block corrosion, without pulling everything apart?

    Thanks,
    Michael
    Michael,
    This is where my "That's another problem" rears its ugly head.
    Oil in the coolant. This can occur when corrosion in the block breaks through into the oil filter housing . This will allow the greater oil pressure to enter the cooling system, over coming the much lower water pressure forcing coolant out of the expansion tank.
    To test for this, remove the oil filter, pressurise the cooling system and observe inside the filter housing. Coolant may appear. It may need testing at slightly higher than the normal cap release figure to achieve this result.
    Another thing, if the contents of the exp tank look like a strawberry milk shake the auto trans cooler in the radiator is leaking. Fit an external cooler to fix.

  11. #11
    Fellow Frogger
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    The usual reason for failure with the Volvo V6 is either the liner seals at the bottom of the liners allowing the liner to settle just enough to cause a blown head gasket OR the block corrodes. Later liner seals were apparently improved but they will still eventually fail. They come in different thicknesses to set the required liner protusion above the block face. A slight leak will only get worse. If your 760 has the original motor you are doing well! My father had a new engine in the early 90's for his 760 due to the liner seal problem. The block corrodes in a variety of places, but that usually shows itself by coolant leaking out the side (look behind the alternator too) or oil and coolant mixing. In my (now long gone) 264 it corroded through into the main oilway at the back so that the coolant was full of oil, but the oil was perfectly clean. It was about 10 years old at the time, the heads were in perfect condition and it ran very smoothly despite the oil in water problem! If you need to do the head gasket and want the car to be a reliable longer-term proposition, you really want to consider replacing the liner seals too to prevent it recurring sooner than later - a much bigger job though as you have to dismantle the bottom end ... If there is insufficient liner protrusion, your new head gaskets may not last long. The head bolts require an angle tightening procedure too.

    The high temperatures may be caused by some internal blockage in the block. That would be possible. Open the drains on either side of the block (towards the front I think) and see what comes out. If you get a lot of rubbish, then it may be fouled up around the liners. Try flushing. I don't suppose it could be your water pump with a badly corroded impeller? If you get that far, be sure to check/replace the valley hoses and pipes as they are hard to get at with the inlet manifold in place.

    I suspect you will really need to do some dismantling to solve the mystery. You really won't know how good or bad the block is until you pull it apart, remove the liners and clean it up.

    Good luck!

    David

    p.s. If you have worn out rear self-levelling shocks you could replace them with regular 740 parts but it doesn't ride anywhere as well. It's relatively 'bouncy'. My father had this done to his 760 a few years ago, but in retrospect it would have been better to pay the (lot) extra to get the original setup overhauled. I think Boge agents can supply the correct self-levelling shock absorbers (Nivomat I think??) and they will surely be much less than the Volvo price. If you are in Sydney, consider A-Class Dismantlers - helpful and reasonably priced.

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