How would you repair broken manifold bolts on a Cat 953 3204 engine?

I noticed my machine a Cat 953 with the 3204, 4 cylinder diesel engine was starting to run warm. The engine was getting a fair covering of black soot on the fuel system and manifold side. Upon examining the manifold a bolt head popped off and it blew out the gasket. Machine was on mission critical job so I ran it for a fat week or two like that. I brought the tractor back to shop and proceeded to removed the exhaust, turbo misc things around it and I raised the cab and installed the safety bar. Most of the exhaust bolts needed a gas axe to remove. 5 bolts broke off in the head and 1 was already broke so 6 of 8 locked into the head. I used a welder and was able to get two out by welding nuts onto the studs. One took 3 attempts and one was easy. The long large center bolts 4 of em, were a different story after welding 3 nuts on each one and each time the bolt snapping there was nothing left to weld to. 2 days into this. I used a centering punch and located the center of the bolt with an punch. After starting to drill the holes in the broken bolt the drill still moved off center. I had hopes of an easy out working but that was a joke. The bolts were basically rust welded to head. I tried a torch with heat no go. Before the drilling began I should have went full stop and built a drill guide plate to ensure the bit went where it was supposed to. But I felt I could get the hand drill close enough. It walked slightly and also leaned about 2*s in the wrong direction. No big deal there should be enough play in the manifold... Nope it was too tight and about impossible to open the existing hole up to give it a little play. The manifold has hardened and it was eating standard drill bits. I tried a nice reamer it cut about 1/2 way and also burnt up. I tried a grinding stone and it burnt that up. I ordered some carbide deburring bits for a die grinder to see what that does. The old manifold is ruined i am using it as a guide to make sure everything will work with the new one that is on the way. So after sleeping on it, now day 3 rolls around. Two bolts are going in but one due to extreme pressure has ruined 1/2 the length of the new threaded hole I made. These are 3/8s x 16 bolts. I decided to make a set of 4 hardened studs to put in the hole and use a nut to hold the manifold on the studs. This allow me to deepen the holes in the head so they had a better bite. Hand tapping the 4 holes is fun luckly, I have some excellent old school burbank tooling that held up to the cast iron. I did not do a perfect job because small parts of the old bolts were in my threads. I took a torch and corrected the stud angle at the head. Bent them slighty. So the old manifold now goes on. I just need to cut out a little metal to get it to slide all the way down. This repair is going to take 4 days and is not perfect. I feel like the grade 8 bolts I cut down and threaded will be ok for the studs. Do you think my repair will hold? Any of you pros have better methods? Or suggestions for a better job?

Me personally id have pulled the head and sent it to the machine shop it probably needs a valve job. Make it a them problem or find another head what kind of shap is the gasket surface in

Cat does have a drill guide for manifold studs but I can't remember if it fits 3204 it has a lot of different configurations it has hardened guides small pilot drill and tap drill sizes only thing we used to say is don't drill till you hit green Meaning don't drill into water jacket it was always a good idea to mark your drill bit on a good hole before drilling. It sure made that job lots lots easier.

pittsburgh cat man said: Cat does have a drill guide for manifold studs but I can't remember if it fits 3204 it has a lot of different configurations it has hardened guides small pilot drill and tap drill sizes only thing we used to say is don't drill till you hit green Meaning don't drill into water jacket it was always a good idea to mark your drill bit on a good hole before drilling. It sure made that job lots lots easier. Click to expand... The ones ive seen only did 33 and 3400 series

Tyler d4c said: Me personally id have pulled the head and sent it to the machine shop it probably needs a valve job. Make it a them problem or find another head what kind of shap is the gasket surface in Click to expand... I believe the head surface is still fine. I think a new gasket will fix it. Any one ever tried using two gaskets? The manifold was burnt up on the right side and cracked so it is junk. The riser has broken bolts in it also have not messed with it yet. Common sense tells me that it should all be redone head included because it is probably designed to all wear out a the same rate. But me trying to save a dollar is going to run it some more, till it breaks somewhere else. The machine runs good and does not have any gasket issues. It might now that I put so much heat to the studs. Who knows...

Tyler d4c said: The ones ive seen only did 33 and 3400 series Click to expand... Same recollection here. Like Tyler I think I would have been pulling the head and let a machine shop tackle it with a vertical borer.

pittsburgh cat man said: Cat does have a drill guide for manifold studs but I can't remember if it fits 3204 it has a lot of different configurations it has hardened guides small pilot drill and tap drill sizes only thing we used to say is don't drill till you hit green Meaning don't drill into water jacket it was always a good idea to mark your drill bit on a good hole before drilling. It sure made that job lots lots easier. Click to expand... What kind of money does Cat charge to fix something like this?

Tyler d4c said: Me personally id have pulled the head and sent it to the machine shop it probably needs a valve job. Make it a them problem or find another head what kind of shap is the gasket surface in Click to expand... How do you know if it needs a valve job?

Georgia Iron said: What kind of money does Cat charge to fix something like this? Click to expand... In general, unless it was a big dealership with their own in-house machine shop, a Cat dealer would farm the job out to an external supplier. Cut out the middle man and send it there yourself would be my best suggestion.

Georgia Iron said: How do you know if it needs a valve job? Click to expand... It may not but if it has any hours on it it very well could good chance to give it some tlc

Nige is there a reman available?

Tyler d4c said: Nige is there a reman available? Click to expand... There may be but I am out in the sticks @ the moment with no access to check (didn’t bring computer on purpose). When I get to town tomorrow I could take a look but need the machine Serial Number to make things easier. Pricing a Reman component might cause the OP a sharp intake of breath.

It is a later 20z 03338

a quick google brough this up. A bit rich for me

OK, so that is an Upgrade-to-New (UTN) head where the buyer gets a brand-new component for his used Core. Is there a price for a Reman (refurbished used) head.? It ought to be about half the price of a UTN head.

Have done a lot of them with a home made steel block about 1.5 inches thick with the correct hole in it for installing a 3/8-16 heli-coil drill bit. I used a new manifold gasket for hole location. Went to further holes out for securement and clamped the block down. The ones with bad threads got heli-coiled and installed new OEM Studs. The ones I did were on Komatsu D85 and D155 engines. They worked. Have welded out lots of them on 3306 and 3406 engines with a washer below the nut I weld on. Used some special Xergon HPM 1000 rod and they all came out. Trick a guy showed me was to use vice grips on the nut so that you can feel if anything is letting go in small movements. Use and electronic helmut to weld and bolt another plate to head to start the rod on and jump onto the nut with rod red hot. That is one of my tricks Simon C

Yep one broken bolt and blown gasket can turn into a $5000.00 repair. That manifold is common $175.00 and lots of choices on ebay. Got bins of bolts laying around and 2 gaskets was 20.00 The carbide bits were another 100.00. Hopefully i can button it back up and then start rebuilding the lift cylinders.

Simon C said: Have done a lot of them with a home made steel block about 1.5 inches thick with the correct hole in it for installing a 3/8-16 heli-coil drill bit. I used a new manifold gasket for hole location. Went to further holes out for securement and clamped the block down. The ones with bad threads got heli-coiled and installed new OEM Studs. The ones I did were on Komatsu D85 and D155 engines. They worked. Have welded out lots of them on 3306 and 3406 engines with a washer below the nut I weld on. Used some special Xergon HPM 1000 rod and they all came out. Trick a guy showed me was to use vice grips on the nut so that you can feel if anything is letting go in small movements. Use and electronic helmut to weld and bolt another plate to head to start the rod on and jump onto the nut with rod red hot. That is one of my tricks Simon C Click to expand... I tried a 6010 rod and a 7018 rod and the washer on the last attempt. Once when I was tapping the weld flux/carbon off the bolt just snapped. The bolts where very brittle. But they were surprisingly easy to drill out. I sharpened the bit about 4 times for each bolt and stepped up in drill sizes. What actually got me was I should have slowed down and looked the old manifold over better before I tackled the center bolts. The drilling out was later in the second day. I was thinking they would let go and come loose but they did not. I did use a guide to set my puch mark but as it started cutting it moved just a little. I also thought they were all short bolts, so close, would have been fine. Those being so long made the tolerances much more important.

Nige said: OK, so that is an Upgrade-to-New (UTN) head where the buyer gets a brand-new component for his used Core. Is there a price for a Reman (refurbished used) head.? It ought to be about half the price of a UTN head. Click to expand... Thats the only number ive found

I actually saw quite a few 953s do the broken bolt cracked manifold thing I don't think I would be too worried about a valve job I'm sure if you get the exhaust leak fixed it will run a lot better exhaust leak equals low boost