Dear Bob: Thanks for the response; \'twas very helpful. I did not notice any posting from Steve Birch; did I miss something? When you cleaned your manifold with acid, how actually did you do it? I\'ve seen kits available based on muratic acid diluted that you hand-pump through. I\'ve heard others suggest vinegar and water--but how does one get the liquids (to include your favorite, sulphuric acid) into and out of the exhaust manifold? <Woody>
Bob Carlisle <bobnlesafloat@...> wrote: Mine has the metal (immoveable) rod in there too; I\'d assumed that it was perhaps originally sprung in some way in order to allow a route for cooling water prior to the thermostat above it opening? In any event; I really wouldn\'t panic: -
Our manifold suffered from a water leak from immediately below this point; as the manifold had corroded away there over the years. In desperation I eventually cleaned up the whole area and re-built the manifold using one of the proprietary epoxy/metal filings metal repair pastes and despite my best efforts I managed to bung-up what if any passage of water had been going through there at the same time. At this point I decided to bolt it back together and pretend it didn\'t matter. That was two years ago and It has made no difference whatsoever to performance since and the water leak has never reappeared either.
We did at a later date suffer an overheating problem (Engine starts; water from exhaust; but overheated after 25 - 60 minutes depending on load.) This turned out to be the thermostat itself which had failed and so was no longer opening (Remove it and throw it into a saucepan of water and slowly boli it up to test.) Given that we were still getting some; though obviously not enough water through the exhaust; this did confirm that the lower/plugged waterway obviously isn\'t vital.
Our initial cure was just to rip the guts out of the thermostat and \'free-flow\' the cooling water and I was since told by Steve Birch that a fair proportion of the UK Vegas are now doing this as a permanent cure because new thermostats are bloody expensive. It struck me that this would result in the engine never reaching operating temperature so I bit the bullet and bought a new one from Volspec - Steve was right; it cost us about £40 with VAT & postage (the \'standard\' thermostats sold for £6 or £7 in any auto-parts shop are fractionally smaller in diameter and more importantly, do not open until a much higher temperature that is required on the MD6A.
No problems since.
I\'ve just seen SB\'s reply suggesting the exhaust manifold too; we suffered from a blockage on that too some years ago which I\'d forgotten - I too found it was a fiddly/laborious task to scape out, so filled it with some sulphuric acid which I had to hand, for about 20 minutes; which worked a treat. Though unlike me I\'d suggest drying it out first - I was just too late in remembering some vague advice from a chemistry teacher of 30 years ago about mixing powerful acids with water. Luckily I did manage to remember what he\'d said you should do if you\'d chosen to ignore the advice, so apart from a few \'tingles\' around my face and a seriously buggered tee-shirt all was well.
Bob Carlisle
macksnap <macksnap@...> wrote:
Hi: wondered if anyone had an experience with the thermostat housing
in the volvo md6a diesel? Removed, one sees the thermostat and below
it a small hole with o-rind surround. On my block this hole seems to
be blocked my solid metal, as if welded shut, while the corresponding
hole on the housing was blocked. I reamed this out Currently
overheating, the engine works otherwise well. Should this hole in the
block be open be open? <Macksnap>
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