Engine is a Toyota 3 litre naturally aspirated indirect injection 4 cylinder diesel with a cast iron head. It had either a cracked head or a leaking head gasket at 460k km and I decided it was worth a rebuild as I had just done brakes, wheel bearings, suspension, etc. I didn't have time to do the engine so found a shop a sent it in. Got it back yesterday, found the bolts holding the power steering reservoir onto the frame just started, pointed that out to the shop, was fixed. Everything else looked good, trailered it home as wasn't available to drive me to shop. Have been fixing a few other non engine things and looking it over and can see that they have used new bolts instead of the old studs for at least one exhaust port I can see sticking out from under the heat shield. I was under the impression that studs are always used in exhaust ( and intake) manifolds. Have I just paid good money for a dodgy shop to do a half arsed job on my engine? Thanks
My cummins are all bolts, not studs, for the exhaust, as are all of my GM trucks. Whats the parts book say?
The 360 Magnum in my old Ram was a mix of bolts and studs on the exhaust manifold. No idea if it left the factory like that or not but they survived the 5 years I owned it and judging by the rust on them when I got the truck I think they were originals. So about 12 years or so they held up.
Service manual is studs and as stated, were factory studs in it when it went in. Again it might be a case of a little bit of knowledge being dangerous, I have never heard of bolts in a manifold before. They have used new bolts so if bolts are OK, then it mightn't be the dodgy work I was becoming concerned it might be. Thanks
A lot of older engines had manifolds bolted in place. Being a non turbo engine I'm pretty sure it should be okay. The original studs may not have been reusable and replacements from Toyota may have been prohibitively expensive and availability may have been a problem as well.
A large percentage of Cat exhaust manifold fixed using bolts. In fact it's unusual to come across one with studs/nuts these days. To me the critical thing is the length of the bolt or stud. A lot of exhausts (no idea about your Toyota) have thick washers or spacers under the nut/bolt so that the correct stretch can be put on the fastener when it is tightened. So the question is did the studs have spacers under the nuts or just washers and do the replacement bolts have the same.? It's a Hilux engine I take it.?
Yeah sorry, 2000 model ln167 Hilux, 5L motor. No washers or spacers, just a new gasket. Intake side is a mixture of what appears to be new bolts and old studs. I don't recall what was on the intake side I want to say studs, but am not sure. I do have another hilux up at one of my properties, it is a 3L motor which was the series before this one so isn't really relevant but I'm heading up there this arvo so wil have a look.
The problem with using bolts instead of studs is threefold; (1) Studs assist in supporting the manifold during installation, making installation easier. (2) Studs normally stay in the head, and the threads in the head are not normally used repeatedly. Repeated use of threads in the cast iron head creates wear in the threads, and the bolt threads are likely to end up a poorer thread fit, after several unscrew/screw-up cycles. Threads in cast iron are more brittle than threads in steel. (3) Using studs and nuts provides better torquing results, as the bolt twists along its length, as it's being tensioned - which affects the final clamping force. A nut on a stud provides a consistent torque result, as the stud and nut are both steel, whereas the steel bolt screwing into cast iron produces a variation in torque due to the surface properties of cast iron and steel being different. Plus you can use a "high" nut to provide more retention strength. A bolt is only as good as its head retention ability. And finally, you have the ability to select the washer O.D., thickness, and hardness, with a stud. Manifolds are subject to intense regular vibration, and having fasteners that are a good fit and provide good even clamping force, is important. The vbration forces come from the engine itself, and even from the driveshafts. An out-of-balance driveshaft can shake bolted engine components right off.
My thought on looking at the (tiny) picture you posted is that someone who takes pride in their work did a nice clean job for you. Joe H
You got a diesel Hilux?
Flange bolts, I wouldn't worry too much.
Studs are good but unless you get high quality or specialized ones, capscrews of gr8 or 10.9 may be better in my opinion. Some OEM studs and capscrews for exhaust components may be a special alloy to compensate for the high heat and expansion and contraction so hence, the high cost. But, harder studs can be more difficult to remove when they break off.
Both studs and bolts will have issues with too much length. Series 60 14L prone for blowing exhaust manifold gaskets,{bolted} mostly due to manifold design, 12.7 not so much. Cat 7FB-3ZJ another that uses studs fail regularly. Then there was that chevy thing three long studs holding the hear riser-sure to come loose and leak or studs would snap off. Brilliant design.
Shoulder bolts, much better than studs IMO.. “looks like” a nice clean job..
Thanks for the replies all. I was pretty happy with the shop, they said all the right things before I gave them the job, price was right and it was done quicker than they originally said. I was a bit put off by the power steering reservoir bolts being loose, not finger tight, literally one or two threads in, but mistakes are made, so I wasn't to concerned at that time. But when I saw the manifold bolt, I thought it may have been a cheap and nasty job, clean on the outside and rubbish on the inside. I usually know just enough to get myself out of trouble, but sometimes just know enough to get myself into trouble. This was one of those times, as stated I have never seen bolts in a manifold before. Thanks for putting me on the right track.
Speaking of the old GM exhaust studs on the heat riser, i always preferred to use brass nuts on them. They seemed to stay tighter and were easier to remove
I would like to know why some engines manifolds leak no matter what and some dont. Old ford engines leaked bad and were not easy to fix. I was under my GM pickup and locked up to see 3 manifold bolts were gone on one side . It hadnt leaked . I put new bolts in and 2 years latter it steal hasn't leaked.
I think of the battles and patch jobs on exhaust manifold studs on engines like my 3406B . Someone had tried to drill the ones near the rear of the engine in place ,drill bit taking the easy route into the head leaving a botched up couple of holes with remains of studs. I managed to extract the remains of the studs and faked it back together with new studs and Belzona. So far so good. I like 56Wrenches idea of using brass nuts . maybe something like a silicon bronze deep nut on those studs might be the real answer. At least they wouldnt rust to the studs.
The issue as I see it for the manufacturers in using brass nuts on studs is cost. Also consider that using a bolt you only have 1 threaded joint versus two if you are using a stud, even though it’s all in the same fastener. IMO on the subject of manifold fasteners loosening it’s all about getting the correct tension on the fastener to allow it to stretch and contract as the engine heats/cools without either loosening or breaking. As an example some of the exhaust manifold bolts on 3500s these days have spacers under the bolt heads that must be 1-1/2” long.
Recall the same kind of thing on the 3300, 3400 series engines and probably a few others. One problem I saw more than a few times with some engines was they had slip joints connecting manifolds sections together. This allowed for movement from heat cycling. Problem was after a period of time the joints would seize up from rust and carbon. Next thing you knew you were breaking head studs. Those would almost always be flush with the head and a real pain to remove at times.
3500s are/were prone to that. Our MO was always to polish the bejasus out of the slip joint parts when rebuilding/repairing until you could almost see daylight through them even when they were assembled. At least that way you had a fighting chance that the manifold sections would find their natural position before everything seized up for good and it wouldn't break so many bolts. Obviously working 24/7/365 helped because engines never really got cold once they were heated up. I've been fortunate over the past few years to have come across a couple of welders who were dab hands at getting broken bolts out of 3500 heads.
I've had several vehicles with the Ford 5.4l and 6.8l modular engines. Every damn one of them has had the exhaust studs break causing manifold leaks. My current F350 has had broken exhaust manifold studs for quite a while now and is low on my list of stuff to address. With the v10 on a 2008, the recommended process is to remove the cab, then fix the studs. I asked my father in law and he laughed. Said its an all day job, whether you lift the cab or not. Its just you spend less time on the studs if the cab is out of the way.
Why does Ford do literally EVERYTHING the most ####ed up way possible?
Just like everyone else - let's squeeze 10#s of crap into a 5# bag, and make it the most cost efficient way to assemble on a production line. They don't care what it takes to repair it later. We just need to build it as efficiently and cheaply as possible.
Ford was ahead of their time. Back in the early 2000s I'd never heard of Dodge or GM having to pull the cab to do engine work.
I own Fords . Not sure if they are better or worse than the others ,its just been my preference. I just have to wonder where some of the designers heads are at . A simple thing like an oil filter was always hanging off the underside of the engine . 2006 comes along 6 liter diesel they put the filter on top of the engine, pull the lid off pull out the filter,perfect no mess of oil drooling over you. 2015 comes along new truck has the frigin filter hanging under the engine catches rocks well when your on the logging roads ,gotta spear it with screw driver to drain it before you unscrew it ,drools oil all over . try changing the AC pump without pulling the cab off. Even my old 4/71 Detroits have a drain cock that you can empty the oil filter with. Where are these designers heads at??
Put quite simply that nowhere in the design brief from their company does it state they have to make whatever they design maintenance-friendly. All they are trying to do is build something that fulfills its stated design function at the lowest cost.
My 6.8l v10 has the filter underneath, but easily accessible. My 2012 5.4l has filter pointed forward off the lower front of engine. Slobbers oil everywhere on the chassis when changing it. Ford put a catch pan there that doesn't catch the drain oil either. Brilliant. Just brilliant.
Exactly like my 5.0, not a drop comes out of the little plastic funnel under the filter but it'll drain out of literally every spot in the skid plate under front diff. Its a 2 drain pan ordeal to catch it all and even then it still makes a mess on the floor.
Engineers I've never met one that thought a tech would actually have to work on something they designed
The illogical aproach to design in todays pickups is depressing ,we d best get back to exhaust studs. Id go with studs given the fact they usually are threaded into cast iron . Thread length can be be chosen the accommodate the dissimilar metals,shoulder length for expansion and contraction. Longer shoulders on the stud allow for spacers and washers . over size holes on the manifolds allow for movement of the manifold. Just need to get around the nuts seizing.
You all have pretty well nailed down the issues with exhaust manifolds and the holding hardware. The instructor at a Cummins school I attended years and years ago put the tightening script down to this. Forget the torque wrench. Tighten the hardware only enough to make sure there are no leaks. For me that was tighten things until the manifold is mated to the gasket and the head and then finish with about a quarter turn on each working from the middle to the ends. One other tip that he gave us was to use grade 5 hardware. His thought was that there would always be problems with the hardware if the engine stayed alive long enough and a grade 5 was a whole lot easier to drill out. My last observation on this has to do with the gasket materials used in the fifties, sixties and seventies compared to what is used now. Asbestos was great for exhaust manifolds back in the day, until you had to peel it off somehow. The manifold would be glued so hard that you could have taken out most of the bolts and the junction was still held fast. These paper thin pieces of stainless used now work OK on a new engine or head but may never seal fully on surfaces that are half way though their design life.
The reason exhaust manifolds be it car or truck have issues is thin wall castings. In the 80's GM went to light weight castings, exhaust manifolds would pull in from the ends, would have oversize holes to start bolts. Then some came with bridge bar between the ends to stop that, those became hard to find. Detroit Series 60 late engines 14L have a problem of cracking at turbo riser, if compared to the 12.7L, the 12.7 is a slightly heavier manifold. GM went to light weight cylinder head castings in the 80's those had issues cracking between the seats. As mentioned above it's all about cutting costs.
They slip joins on the 3406B were a great idea until they get old and seize up
I use these-work perfect for any situation, especially drilling out broken studs & bolts, goes through stainless like a dart. Winzer Shoppro Cyclone drills.
Never seen those bits, where do you get them? Joe H
I rarely get any problems with exhaust manifold bolts with adequate spacers and plenty trouble with no spacers. I throw away the book on this. Before I got into spacers ,I tried up grading to 10.9 and 12.9 bolts which broke more and were extra tough to remove. I now only use 8.8 grade off the shelf bolts and add spacers if not already there and always use a torque wrench set to 80 to 100% for the bolt unless it is an alloy head. Apart from holding up gaskets i cant see much benefit from studs. Cool drill bit
Those step point bits are the **** for everything.
Why wouldn't you use nickel-based anti-seize on those manifold slip joints? The best varieties will withstand 1427°C or 2600°F.
Matco, Astro Pneumatic, Norseman, Kimball Midwest. Astro was running a deal on them,.not sure if they are doing it for the Holidays again.
I’ve tried using a couple different types of anti-seize on expansion joints but eventually with high manifold temp( full engine load), they still seize
Running D342’s in my D8’s in the wing and a prayer days,I often found myself replacing head gaskets on them on a Saturday afternoon.This was primarily due to the usual liner heights not been right,but they could easily keep limping by year after year. This would result in the manifolds having to get removed and replaced.I allways,allways used new Cat studs(even when money was tight).They worked well and I don’t recall any issues with them.The problem was that they were a bugger to seal at the couplings and I fixated on all sorts of ideas to stop the smoke leaking out.Tins of gum gum and asbestos bandages were allways to hand in the pickup.I laugh now when I look back. The other problem,was cracking the manifolds after a while,allways the rear one.To be honest,they didn’t leak when cracked and I never lost sleep over them. One day,I mentioned this to TC Tractors,and he told me to slightly oversize all the holes in the rear manifolds when I next had the motivation. It worked! From then on,the leaky couplings were allways easier to seal,and stay that way.No more cracked manifolds either. As for torque settings,I would just run the new studs in with a couple of nuts,then nip them up.After that,I’d check them every day for a few shifts when hot,until they seemed settled. Probably the wrong way to do the job,but seemed to work ok. There are times in my life that I’ve tried to do things by the book and gotten poor results.I’ve put this down to the fact,that most of my kit was old and probably out of manufactures spec and also the fact that I’m no fitter,just a jobber
Cat installed heat wrap and shields for exhaust manifolds on-road 3406's, Worthless it was.
I need one of you to get me some of those drill bits for Christmas
You need to write a letter to Santa first, telling him how good you've been this year.
3500 engine experience - nothing works. As I said before the best bet is to open up the clearances in the slip joints signifcantly; we would even use a stone on them. Strangely enough this is similar to what Nicky is talking about from generations ago with TCT's advice regarding opening up the stud holes in the mainfold. Simple fact is that heat expansion/contraction breaks fasteners, especially when you have engines with multiple cylinder heads and multi-piece exhaust manifolds all trying to move in different directions.