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Thread: solid chain tensioners or Pressure fed??

  1. #1

    solid chain tensioners or Pressure fed??

    I'm building an engine and the builder recommends solid tensioners because he feels they are foolproof as long as one adjust them when they get noisy. He has seen pressure-fed tensioners fail and knows of a recall of defective lot orders floating around. I have a set and I'm trying to decide whether to install the or not. Any mechanics out there with an opinion?
    Thanks in advance

  2. #2
    Go with the pressure fed. Most mechanics will look for any excuse to get you back for something. By the way, unless you have a question concerning lights or carpet colors, these dip****s don't have a clue.

  3. #3
    Roland Kunz


    Those mechanical units where made for use in race cars. Using them in the engine starts to wear out the cam gears and the chain much faster then with a stock tensioner.

    Now race cars are not made to be used on short driving and do not see too much heat cycles compared with a street engine.
    Race engines are maintained on a shorter period. Sometimes daily after use.
    Race engines do not have the usuall valvetrain they have a much lighter top end with non valve adjustment rockers.
    Race car drivers mostly are very sensitive to noise changes siting in a empty loud sheel with the engine boltet solid to the frame and having a helmet on you feel and hear a complete different way.
    Race mechanica are also more sensetive and can hear and feel every difference. They also can decide if they should quit the race to save money or let it go on to find out how loud it will get.
    Race engines where not made to run very high milages.
    Having serviced several engines made by Feustel ( 901 2,0 210 HP ), Rugen ( 901 2,0 225 HP, 2,5 RS 280 HP ), Wagner ( 2,7 RS 250 HP, 3,0 RS 330 HP ) non of them had a mechanical lifter.
    As you have to rebuild the top end on a regular basis you just renew the 930 tensioners. A 2,0 with 210 + HP will run some 20 000 - 30 000km between head and P&C services.

    Now the pressure fed tensioners have some problematics.

    1.) they have as far I could see it the same failure rate alike the normal 930 tensioner. They seem to fail very soon if the oil contains to much dirt. Also there had been a series sold mostly via the aftermarked who failed within several hours.
    2.) they need a very proper installation routine if you set your cam timing with them and use them to hold the cam via the chain they will fail very soon.
    3.) they also will fail if the engine is runing over 6 bar pressure. The 930 cases have a other oilpump and a modified case, as long the old block isnīt upgraded to the new standard I wouldnīt recomend using them. They will hold very long but will start needing more time to go up after coldstarts and if your overpressurepiston stucks the unit will shot off his vent ball and let colapse the unit.
    4.) After several years working on Porsche and listening to hearsay and stories I found the failure rate from the 930 unit is very low much lower then the pressure feed units. In fact I nver had a failed 930 tensioner on my engines but lost several pressure feed units. Failed 930 tensioners had very high milage and those engines also has bad ramps and worn chains keep beating on the unit. I think BA recomend to renew them every 50 000 mls I use to renew them on every time the heads have to come off with is some 100 - 200000 mls for the average driver.

    Now print out the thread and show it to your mechanic.

    I would not upgrade to pressure feed tensioners as long the fundamentals are not achived.

    I have no doubt what engine you bild and what your goals are.

    I would stick to the original 930 tensioners or just try the mechanical units. They can be swaped within short time.
    Following the US boards most recomend to use a colapse protector ring on the tensioner.


  4. #4
    Semi retraction- at least one person has a clue.

  5. #5
    I take it that there is a difference between solid tensioners and 930 tensioners? The engines that you serviced, Wagner ect..did they have press-fed tensioners or 930 style tensioners?

  6. #6

    930 tensioners or pressure fed?

    If you don't want to up grade your oil pump I would stay with the 930 tensioners. I would not use the solid mechanical tensioners under any circumstances! I have an early 911S and was told I would I would lose some oil pressure if I used pressure fed tensioners. Also at the time there was a back order sitution and that told me that maybe Porsche was changing the pressure fed ones. Also very important is using the newer Idler arms with the brass bushings as these will keep the arm from galling the shaft it sits on.

  7. #7
    Roland Kunz

    OK, sorry, I have to start at a earlyer chapter.

    The first "indipendend" tensioners where the 901 units, then the 911 units followed and with the 930 engine came the last stage.
    With the MY 84 3,2 and the 3,3 930 the oil feed pressure tensioners came.

    The 901 tensioner looks very typical and is not used anymore. It had a cuped upper end to feed oil mostly splashed in by the chain and the oilflushing in curves and under accelerating. Those units had a high failure rate and startet the bad reputation. The failures where mostly startet by excesive wear and the left unit didnīt see enough oil on constant driving at low revs on the highway. But the units also had failures by soft bashed springs. Those units bear a 901 ordernumber in the case.

    In 1970 came the complete new, now capsuled, tensioner having a 911 ordernumber. The failurerate droped but stiil some failures showed up.

    So Porsche improved it to the 930 units coming with the turbos and later used in the SC too.

    The difference from the 911 to 930 is the way they fail. The 911 lost the oil and then didnīt came up.
    The 930 units are much harder using a higher base spring load. To compensate the load to the chain the new chain ramps coming with the 911 got other damping charactersitic and improved material.

    Using the new tensioners on the old chain rails will brake them on the long run and then they "snap".

    As the parts got superceded you only can determine the status by checking for the single brown "anti noise" ramp. You will find it on the right side at the upper ramp from theintermediate shaft gear.

    However if you still have the old ramps replace them in the next time as they get briddle over the years ( Some say the new synth oil speed it up and I have the similar feeling ) and can brake then. If you still have the rubber units get them out soon too. TO check if you have rubbered ramps just open your old oilfilter and look for fine black particles. This is the cam tower oillinekiller. The rubber gets brittle over the time to but the new oils speed it up especialy the newer full synth will loosen all dirt but not bind it inside the structure to transport it away to the filter. As long you have a good filter and keep the oil change intervall to the specs there is only a minimal risk to see the rubber in the main gallery but @#%$ happens.

    If you had the ruberized ramps you need not to think about upgrading to the pressure feeded tensuiners as they are more sensetive to dirt then all the other engine parts.

    If you upgrade to 84on units also make sure you have the supports for the small feedlines on hand. They will avoid failures caused by vibrating loose fittings ( AFIK it happend on race cars ). Also make sure you have the spacer ring behind the tensioner and check if a small ball is a top of the tensioner blocking off the regulator/vent hole.

    The large benefit from the units is ther progressive working keeping the strees in the system at the lowest possible level. They also will start making noises if they are worn and people will hear it. On the other side the oilpressure will pump them up enough to work good enough for a long time.

    Now the usage from the pressure feed units ( PFU ) was very comon and everybody made the upgrade. Mr Wagner ( A old Porsche race mechanic who left Porsche with the jung guns ( F.P & F.A.P )) was allways suspect about using them in ancient engines and used them only if the costumer insistet on it. We had several times talked about the subject and he also is strictly against using the mechnical units. He just says that they where used short time to replace the 901 units. On the old 901 engines the intermediate shaft was runing direct in the aluminium and the solid units put to much load on the shaft causing the case geting oval and let wiggle the shaft until it brakes. So in the first time the had many failures untill they had a fix for that. Also the solid units could support braking chains. So on most race engines where the 901 tensioners used again. They made some "tuning" to them and got a regular service check.

    Porsche also had the first PFU in testruns in the late 60īs. The system was to big to fit inside so they placed them outside and used a leversystem to transport the load inside.

    So this is maybe the background why some race engine builders are not using solid units. Feustel is well known as Racliene and makes the 901 race engines for Porsche. And Manfred Rugen is the coming star in the young generation.
    His engines are in many well known cars ( E.e.: Vic Elfords 901 R ) in europe.

    Feustel does deliver the engines to costumer wish also with PFU, he recomend them for occasional race drivers or for street/rally use. Those engines are mostly not tricked out and have a normal valvetrain ( but still over 100 HP/liter with Solex ).
    Rugen does similar but doesnīt like to see them in high reving race engines, he just say it is a own personal observation and he thinks that to much heat and oilpressure will speed up failure on them. His reputation are engines that will have the highest power and last as low powered race engines. It is his reputation. However in normal engines and engines that will not rev abouve 8000 he has no problem or recomends them.
    He just found out there limits. I also know he is working on own fail proof PFU for his up to 10 000 engines. He just improves the design to his needs.

    Now my own observation is that I lost to much time and money fixing PFU trouble.
    I also lost a engine maybe caused by a PFU unit.
    However It is/was very comon to upgrade and most of the failuers where coming far out of the waranty time. But after some years you could see the picture and I stoped to use them on pre 77 engines except the engine had been a rebuild. And I also donīt use them in "dirty" engines.
    I do also replace the oil pressure control valve with the spring and check the filter for dirt to have no sleepless nights.

    Now the point is every mechanic makes his own expiriences and has to do what he is feeling comfortable with. As a mechanic you will not have to much time investet in uselees crap or reworking old storys. You try to do it once and then right. Iīm a young mechanic and know the old things from hearsay. In my working time I never had seena 901 tensioner in a working engine. This day might come. But it will be as rareas to find a unventet distributor in a 964 or the factory deliverd battery in the trunk. I feel very comfortable with the 930 units as I allways had luck with them something I canīt say with the PFU. I did react to that problem by going on the safe side for me. But maybe I was followed by the bad PFU straw and other mechanics had more trouble with the 930 units.

    So I donīt say the PFU is a bad thing but I just do my homework and show up possible failure reasons and how to avoid them. I just do decide what to use by thinking about the usage from the car and talking to the costumer. Some just would like to have them to feel they did the best possible to there engines and there is no doubt about that. But it is the costumers choice based on different point of views.

    Short said the PFU has the lowest wear on the system, it makes lower noise and if it fails you will hear it but will not get stranded, you are even ot forced to rush to do the repair.

    The 930 unit is not so money investing and has a pretty low failure rate. If it fails you will hear it and you have to get into repair soon. The system gets more stress and wear forcing to a splitet chain or a complette engine rebuild on the very long run.

    I also have a pair solid lifter in use and I would miss them if I have to make the cam timing.


  8. #8

    solid chain tensioners or Pressure fed?

    I have a 1970 911S and wanted to upgrade my tensioners. At the time if I knew the tensioners that were in use had the hydrostops or guards on the shafts of the tensioners I would of kept them until they failed. I am very glad I did not know the statis of my tensioners at the time I purchased my car. I had to go into the engine and inspect the condition of the tensioners. I almost went for the pressure fed ones but several reasons against the pressure fed pushed me toward the930's. [1] There were some failures with the pressure fed's. [2] Lower oil prsssure with pressure fed's might mean less lubercation for engine. [3] possible oil leaks from added oil lines. [4] they are not used much in racing . [5] You loose the stock look.

  9. #9

    Re: solid chain tensioners or Pressure fed?

    Tensioners. I'm no mechanic, but I did the pressure fed upgrade some time ago. Ramps were changed at that time.
    So far, so good, and I have not noticed any decrease in oil pressure.

    That said, an earlier comment was uncalled for. something about "most of these dip****s don't have a clue", posted by a t150R. Uh, didn't the original post ask if "any mechanics out there with an opinion"? Yeah, I had an opinion, but I'm not a mechanic. How 'bout you, t150R? You a mechanic? If so, want to tell us where you work? Please, enlighten us mere "dip****s" some more. Can't wait to see a post as informative as Roland's...also without the insults, as Roland's post was.

    Why donkeys don't go to college....because nobody like a smartass!

  10. #10
    Scary...When I bought my 72S "everyone" from the dealer to the guy who inspected the car to other 72S owners told me to put pressure tensioners on it. They were like gold dust to get hold of as so many older cars were having them fitted - Porsche was having trouble keeping up with demand.

    I've only done 2k with it since having them fitted so no time for problems to arise.

    What pressure should the car be showing ? Mine sits around 2 all of the time. It only rises up (slightly) if I'm really pushing on. Could well be that the pressure gauge is reading low.

    Is this the right ball park ? It sits at around 80 on the temp gauge when warm.

    I've started to worry about this now ! What oil are you guys using ? I've filled up with Mobil 1 Motorsport but have since been told that it MAY be a little thin.


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