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Trying to diagnose/describe a 240 noise

Hey all,

I'm at an impasse with my car and I figured I'd try see what you folks (by far the best problem solvers for my Volvo) thought might be the cause of my problem.

The car is a 1983 240 Turbo. It's an automatic with 3spd+OD (I am told this was a common mod).

About a month ago I had the timing belt snap at very low speeds. The car just died and, since I was going about 5km/hr I was able to coast to the curb and wait for a tow. The belt was replaced and I was on the road again. The day I got the car back I took it for an oil change and decided to try something new: 20W50. Before you punce on this hear my reasoning: the car temperature has been higher than normal (a little higher every summer) and at one point on the third of several consecutive really hot days the 10W30 seemed to completely break down, registering low oil pressure even though the dipstick said it was ok. After consulting the manual (and checking here) I decided to take a shot at the 20W50 and put it in the day my car came back from the belt replacement.

I mention this because I can't be sure which of these two factors is causing "the noise".

The noise is best described as a METALLIC GARGLE, not unlike the sound large trucks make. It comes in when the engine is under a load, either uphill or accellerating. The sound comes in right when the Turbo boost hits the yellow but if I push through that it goes away again and the normal whine of the turbo spooling up can be heard. Also this sound is coming from the back (or, I suppose, out of the exhaust). Also there might be a little less power than before but things are otherwise normal. If I can drive VERY conservatively I can avoid making this noise most of the time.

One final tidbit: I have been topping up the oil with 10W30 as needed and it has had some effect but has not completely eliminated the noise.

My biggest fear: the Turbo bearings or some key engine component is damaged either by thick oil or the snapped timing belt. Ruled out: the exhaust has been thoroughly checked.

Any ideas?

Thanks in advance, Boris ps. Somewhat related: I got an antifreeze tester and it tells me what temperature I will freeze/boil at. This seems completely disconnected from the units specified in the manual...what range should I want to see? How do I know whether to add water or antifreeze?

Reply to
blurp
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In article , snipped-for-privacy@hotmail.com by blurp dropped his wrench, scratched his head and mumbled,

This is common and is due to silicate build up in the radiator core, either rod out, recore or replace the radiator.

There are two square cut o-rings on either end of the transfer tube from the oil pump to the block. Some were misinstalled at the factory but all harden over time and leak. Once the engine picks up speed the small leak doesn't let the pressure drop to unreasonably low levels. The oil pressure switch is set at 0,5 bar and is dead accurate. If you remove the switch and install a test gauge you will indeed see pressure below 7.5 psi at idle, oil hot.

The exhaust can contact the body in several places, if one motor mount or exhaust doughnut is broken or collapsed, a few more. If the cross under pipe is cracked or a baffle has come loose in the muffler the exhaust note will be affected.

Bob

Reply to
volvowrench

Seems quite possible. Any idea how I would go about testing that or do I just get them changed?

It also occurs to me that maybe a dyno would be a good place to test theories and I may have access to one. I'll keep you informed and see what else I can find out.

Thanks for your input! blurp

On Thu, 7 Aug 2003 05:16:43 +0100, the illustrious "Stuart Gray" favored us with the following prose:

Reply to
blurp

Just thought I'd toss this out here in case anyone was experiencing something simillar.

The "metallic gargle" has been identified by my brother-in-law as "DETONATION". As soon as he heard it the sound it was the first word out of his mouth. He described it as possibly also being linked to the increased temperatures I had been seeing on the gauge (that is, the higher temperatures would be contributing to the detonating).

His recommended remedy is to switch to higher octane fuel (I run Shell Optimax which is 91 octane, he suggested Sunoco 94) and use an octane booster next fill-up and then every now and again thereafter.

For the rising temperature issue he recommended a cooling system flush. Now I have read on this group that radiator flushes on cars this old were not recommended because scale broken loose could clog the radiator up...any further thoughts on that?

Thanks to all who looked at this post and scratched their heads for me. Now that DETONATION has been named does anyone else have comment or suggestion? Anything else I should check or look into at this time?

Thanks for any new suggestions!

blurp.

ps. I'm reposting this with a new heading as well.

On Mon, 18 Aug 2003 11:20:51 -0400, the illustrious blurp favored us with the following prose:

Reply to
blurp

Doesn't detonation cause overheating? Could be your timing (spark) is too advanced eg. it is at 10% BTDC and should be 15% BTDC. Those figures are just example figures not the real ones. I don't have my Haynes on me atm.

Stuart.

Reply to
Stuart Gray

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