91 240 B230 Block Cracked?

brivo · Post by **brivo** » 03 Jun 2015, 21:03

A few weeks ago I noticed a billowing white cloud of smoke in my exhaust, so I stopped driving it and changed the head gasket. Everything was fine for a few days, then the smoke started to come back. So I took the head off and took it to a machinist to get decked. He said the compression test checked out and found a small notch in the head, which he planed out. I put the head back on with a new head gasket, and ran fine for a day or so, but then the white smoke came roaring back.

There's always the possibility I did something wrong, but I followed my Bentley manual very closely, and I was careful to torque the head bolts (which I replaced) to the proper specs with a torque wrench. My friend who is an actual mechanic also gave me a hand. I cleaned the block surface down very well before putting the head back on. I don't think I made any mistakes putting the head and gasket back on.

The only other possibility as far as I can tell and according to my Bentley manual is that there is a crack in the engine block. The car has about 300,000 miles on it, but I always (naively) assumed the cast iron block was more or less invincible. I've had some overheating problems, especially because my gauges have all failed (I recently rigged up an analogue ohmmeter to the temperature sensor to measure the internal resistance of the sensor changing with temperature, but it looks like I was too late). I've always kept an eye on the coolant, and had to add some occasionally, but not more than other cars I've owned. I'm thinking undetected overheating and sudden temperature changes from coolant leaking into the block through the defective head put too much stress on and cracked the block?

I know there's products like Blue Devil out there that might stop the leak, but I know they ruin the engine, and I'd hate to sacrifice an apparently good head for the sake of a junk block.

I hate to give up on this car, as I've had it for about 4 years; does my diagnosis of a cracked block sound correct?

lummert · Post by **lummert** » 04 Jun 2015, 14:55

My uncle once used a proctuct called "Glass Seal" to seal a cracked Chevy V6 block. The local machine shop was using Glass Seal when installing hardened steel valve seats in cast iron cylinder heads.

93Regina · Post by **93Regina** » 04 Jun 2015, 23:47

brivo wrote:head off and ...decked

Head removal and installation must be by the Volvo book; head bolts could be reused on B23s and older, if not stretched, but I don't know if B230s used Torque-To-Yield Cylinder Head Bolts.

I would find it odd that iron block had an issue. Myself, I'd remove head, via Volvo's instructions, and determine where the HG broke. Volvo heads are limited to shaving...so, check to see how level (flat) it is.

How to Use Liquid Glass To Seal A Blown Head Gasket

brivo · Post by **brivo** » 07 Jun 2015, 20:17

I've been looking into glass seal, but I really don't like the idea of using any type of quick fix for internal engine repair. Really at this point I'm worried about ruining the apparently good head, which I might try to reuse later.

I followed the instructions in my Bentley manual to remove the head and HG. Both times I used a hg bought from a Volvo dealership. The bolts are torque-to-yield, and Volvo recommends they only be reused a maximum of 5 times; I used brand new ones both times out of paranoia. I removed and tightened the bolts in sequence (and lightly oiled the new bolts). I torqued the bolts to the specs from my manual in the three stages required using a torque wrench.

I'm also very surprised a cast iron block would crack, but I'm putting my faith in the machinist, who said the head did fine on the compression test, and said he shaved the head enough to remove the imperfection in the head. So as far as I can tell the head is good.

I consulted an old time Volvo mechanic, and he reaffirmed that if it's not the hg or the head, all it could really be is the block. I don't know what I'm going to do with my 240, but I'm buying a new car. Thanks for the advice everyone.

lummert · Post by **lummert** » 07 Jun 2015, 21:56

Candidate for a junkyard engine.

93Regina · Post by **93Regina** » 08 Jun 2015, 11:21

brivo wrote:very surprised a cast iron block would crack.

MAGNAFLUXING CRACK DETECTION

Myself, I'd pull the whole engine-transmission out as an unit, and then put engine on a stand, and tear it down, and have block magnafluxed.

Engine-transmission is going to have to come out...anyway

Salomons Driveway · Post by **Salomons Driveway** » 09 Jun 2015, 06:08

I rebuilt a B230 FT from a 740 last year. It cost about $2000 and took me around 6 months, but was around the same price as a junkyard engine, just took longer. If you think your block is bad, get another engine instead of wasting money to prove it is bad. It costs about the same amount of money, but saves a lot of time. Installing a rebuilt engine in my Nissan only took 2 months instead of 6.

93Regina · Post by **93Regina** » 09 Jun 2015, 16:49

Salomons Driveway wrote:I rebuilt a B230 FT from a 740 last year.

His "heart/mind" are elsewhere..." but I'm buying a new car."