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Post-Rebuild B20 - Coolant Leak

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Old Jul 13th, 2019, 13:38   #41
Derek UK
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Citric acid powder 1lb to 1-gallon imp for a very strong mix. Cheap.
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Old Jul 13th, 2019, 16:55   #42
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Good tip about the descaler. I will use that and flush as adviced. I am sure I can find some trash in the leavings.

I have the original thermostat box. It lists the b18, b20 and b30 for engine type and the temp is 87C / 189F. Last night I drove on the highway in cooler dry weather. The temp is much improved and the worst may be a result of the heatwave.

As for oil pressure- I removed the valve on the flame trap and the pressure at idle dropped by half. To read 2.5 kg. Under highway speeds it was stable around 5, increasing a bit under acceleration or engine breaking. Idle is not unstable.
Ill go without the valve then.

The symptoms I am watching now are how fouled the spark plugs become, as they have been getting dark so far but hard for me to tell if its oily deposits or from richness of fuel mix and heat. I will see how this is this afternoon. In past I pulled them for misfiring at start. I havent had that misfiring for a few days though.

Im still hunting the final electrical short in system that causes tach to die when headlites come on. I finally removed or replaced wiring from engine to dash during build. I have a final string of mess under dash from previous owner I am diagramming before pulling. Difficult access and bad on my back.
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Old Jul 14th, 2019, 19:52   #43
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Descaler is available from a number of places: ~ DIY sheds- ebay or your local plumbers merchants, various brands exist but generally all the same base.

The product is mixed with water (try the initial mix hot) goes a long way as it is generally added to the central heating system.
Once completed flush through a couple of times & then back to the antifreeze mix as normal.

Last edited by Bob Meadows; Jul 14th, 2019 at 19:55.
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Old Jul 14th, 2019, 20:16   #44
Derek UK
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The PCV valve has nothing to do with the oil pressure, it just controls the airflow inside the engine. If the ventilation system is set up correctly there should be just a fraction of vacuum inside the engine. That keeps the oil and fumes inside and directs them to the intake where they combine with the intake air. The late B18 and B20 systems work the opposite way to each other. If you try and mix and match the two systems you can end up pressurising the crankcase and this causes oil leaks. The emissions part of testing in NY may or may not be kind to you if the tester is having a bad day and requires that your engine has the system set up by the book. On the B20 system, there should be a hose from the air filter or filter air box that goes to the oil cap. Air is drawn into the engine from the filter. If you take the oil cap off and put your hand over the hole when the engine is running it should suck on your hand. If it blows the system is set-up wrong. Yes, it is a minefield if you stray from Volvo's system. It's done to minimise emissions and that's that. If you remove the PCV and you have servo attached from the cross pipe you will have problems.
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Old Jul 15th, 2019, 07:40   #45
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On the B20 system, there should be a hose from the air filter or filter air box that goes to the oil cap.

I think this is incorrect. On the B20 The hose from the air filter goes to the oil trap on the side of the engine and the hose on the oil cap goes to the intake manifold.
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Old Today, 00:39   #46
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On Sunday I found a spot on a dirty street corner by by a sewer grate with hardened takeaway grease. This to mask any mess I make as I drain the coolant (No! I wasn't cheating and draining it into the sewer, then to the East River! Truly!). The work was painfully hot without shade. For once- that pain was rewarded with a positive result with the first trial! I've gone from my gauge hitting hot+ to normal readings- in the middle, and either side depending on conditions. The readings I have seen over the past three years with my previous engine.

The flushing may have fixed it. But I think it is primarily the thermostat. The new Volvo one I had in there (made in Germany, old stock) was marked 87 degrees. The one I took out of my old B20 (marked Made in France) had 70 degree markings. It worked fine before, why not try it? Happy I did. Probably thermostat and flushing together, but I doubt I would be so pleased if I didn't swap the thermostat. I have been verifying temperatures with infrared and I am seeing about a 30 degree drop along all cylinders.

There is not much to do about the heat wave. Around 3:00 I did a 15 minute drive with a lot of idling at stop lights and the engine was very much over heated at the end. But it was 94f/34c degrees and in the sun, hotter still. The hottest reading I got on the back of the engine was 221 degrees, 190 at plugs. I won't do anymore drives in that weather when I am not getting on the motorway.

I have done 5 miles on a fast moving BQE (84f/ 28c) and temp was steady in the middle. Went to 3/4 when I pulled off and parked. I think I am going to leave early in the morning this Saturday when we drive up to the Massachusetts's Berkshires. The only portion of concern is the getting-out-of-the-damned-city portion. It's 1/2 hour moving with low traffic or 1.5 - 2 and crawling with traffic. The rest is a little more than 3 hours, though we will stop in towns. I will be avoiding the Big I - interstate expressways!
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b20, engine rebuild, leaking coolant

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