M28/22 is this an interfernece engine??
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From: Philly PA
Thats correct HTD is what you said, This belt gives a better transfer of torque, to the drive and driven pulleys. I would consider replacing the pulleys that will include both cams and the oil pump and the crank driver
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As a side note to this saga--
A leakdown tester is the perfect way to determine if there are bent valves in a motor that is onconvenient to crank with a starter. Roll each cylinder to TDC, Ok to have the belt less than full tight, and do the test. You'll hear a LOT of air from intake or exhaust valves leaking. Don't worry about the actual reading or leakage around the dry rings, just focus on intake and exhaust air noises.
If you have a compression gauge with the interchangeable hoses as I do, it comes with a handy quick-disconnect fitting for the gauge portion; put a small regulator in the line to keep pressure low enough to avoid inconvenient rolling of the crank, say 50 PSI or so, and use that to charge the cylinder for this test using the hose and plug fitting from the compression gauge. A quick-and-dirty bent-valve test for those without a full leakdown test set.
A leakdown tester is the perfect way to determine if there are bent valves in a motor that is onconvenient to crank with a starter. Roll each cylinder to TDC, Ok to have the belt less than full tight, and do the test. You'll hear a LOT of air from intake or exhaust valves leaking. Don't worry about the actual reading or leakage around the dry rings, just focus on intake and exhaust air noises.
If you have a compression gauge with the interchangeable hoses as I do, it comes with a handy quick-disconnect fitting for the gauge portion; put a small regulator in the line to keep pressure low enough to avoid inconvenient rolling of the crank, say 50 PSI or so, and use that to charge the cylinder for this test using the hose and plug fitting from the compression gauge. A quick-and-dirty bent-valve test for those without a full leakdown test set.
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Fabio421 the load on the timing belt would only change IF you changed camshafts to those with more lift. More lift more spring compression more work being done by the belt. The amount of horsepower being made makes no difference 5,000 RPM is 5,000 RPM all the cam drag, oil pump turning , water pump spinning is a constant parasitic loss UNLESS you change the cams.
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From: Philly PA
Dr Bob with the compression numbers I got does it sound like I have bent valves??? I turned the cams both of them whist the engine was at TDC one full rotation and there wasnt any friction, and then I refitted the belt the only low numbers are a 120 and a 125. please share your thoughts
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I wouldn't put a lot of concern with the compression numbers, especially if the engine was cold and no oil film on the walls from recent running. If you were able to see these numbers, there's really no worries about bent valves; A bent valve shows a pretty huge drop[ in cylinder pressure at cranking speeds; You'd generally be lucky to see 50 lbs in a bent-valve cylinder.
If you turned the cams easily with the engine at TDC, consider that the lifters are not pumped up by any engine oil pressure; they collapse a little as you go through the cam rotation at hand-and-wrench speed, and won't pump back up all the way until you have oil flow and pressure to them.
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I really need another borescope, one with a CCD camera and a cable to plug into the computer to watch what's going on inside. I bought a cute little LED on a mini gooseneck disguised as a reading or keyboard light. USB on the back end. Just need a small camera element that will fit through a plug hole. Or I could just buy one I guess.
If you turned the cams easily with the engine at TDC, consider that the lifters are not pumped up by any engine oil pressure; they collapse a little as you go through the cam rotation at hand-and-wrench speed, and won't pump back up all the way until you have oil flow and pressure to them.
----
I really need another borescope, one with a CCD camera and a cable to plug into the computer to watch what's going on inside. I bought a cute little LED on a mini gooseneck disguised as a reading or keyboard light. USB on the back end. Just need a small camera element that will fit through a plug hole. Or I could just buy one I guess.
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From: Not close enough to VIR.
All Swiss, Swedish, Australian, and I think Austrian S2s had the low compression pistons in addition to Al's serial numbers. Their interference is carbon and manufacturing tolerence dependent. All high compression piston S2s would be interference.
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From: Helsinki, Finland
If there is no 45 degree marking in damper I believe such engine is not interference engine. On paper that is. Once timing is even slightly off or there is carbon buildup on top of pistons this changes and valves are known to have been damaged when belt goes.
AFAIK only in '85 and '86 MY M28/22 and possibly M28/21 4.7L ROW S engines were made with low 9.3:1 compression ratio pistons. Cars which had these should have code M151 in option sticker. These were used in cars sold to Sweden and Switzerland, not in many other countries. I'm not sure if engine block has any visible signs on outside what parts are inside. Engine number might not have anything special in it. Some earlier MY Swedish and Swiss models had different distributor parts which affected to ignition timing but this would have been done inside EZT box in S2 I think. If someone has S2 with M151 listed please check what engine stamping on front top of block says.
Australian '86 MY cars should have 9.3:1 low compression ROW 32V catalytic converter engine as stock choice but there are also 16V in there I think. There's still lot of unknown details about these alternative ROW engines. What was sold when and where is all open. Factory documents in circulation do not have all the details. For example what is torque figure on M28/22 M151 engine and what rpm it comes in. If we would have similar yearly changes documents for all ROW model years as there are for US models in Jim M. CD's some of these mysteries could be solved.
AFAIK only in '85 and '86 MY M28/22 and possibly M28/21 4.7L ROW S engines were made with low 9.3:1 compression ratio pistons. Cars which had these should have code M151 in option sticker. These were used in cars sold to Sweden and Switzerland, not in many other countries. I'm not sure if engine block has any visible signs on outside what parts are inside. Engine number might not have anything special in it. Some earlier MY Swedish and Swiss models had different distributor parts which affected to ignition timing but this would have been done inside EZT box in S2 I think. If someone has S2 with M151 listed please check what engine stamping on front top of block says.
Australian '86 MY cars should have 9.3:1 low compression ROW 32V catalytic converter engine as stock choice but there are also 16V in there I think. There's still lot of unknown details about these alternative ROW engines. What was sold when and where is all open. Factory documents in circulation do not have all the details. For example what is torque figure on M28/22 M151 engine and what rpm it comes in. If we would have similar yearly changes documents for all ROW model years as there are for US models in Jim M. CD's some of these mysteries could be solved.
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Australian '86 MY cars should have 9.3:1 low compression ROW 32V catalytic converter engine as stock choice but there are also 16V in there I think. There's still lot of unknown details about these alternative ROW engines. What was sold when and where is all open. Factory documents in circulation do not have all the details. For example what is torque figure on M28/22 M151 engine and what rpm it comes in. If we would have similar yearly changes documents for all ROW model years as there are for US models in Jim M. CD's some of these mysteries could be solved.
Look down the plug hole, if there is a rather big dish in the piston it is a 9.3:1 piston, look in the workshop manual for comparision.
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From: Philly PA
I didnt get a chance , or rather make an effort to check the piston tops but there is not a 151 on the option sticker the car has the following codes 058,249,327,438,454,468,528,533,650. so then this engine sounds like it could have the higher compression pistons fitted, i guess the only real way to tell is to pull a plug and check the piston top