Radiator repair featuring hockey puck turning - 55kw generator

[FliesLikeABrick]

Earlier this year I had the opportunity to buy a non--running 55kw genset for a very good price, after the owner decided they did not want to chase down all the repairs it might need when initial testing and triage showed multiple problems that could be an endless rabbithole.

It is a Detroit Diesel-branded unit, but effectively looks to be a Kohler rebadge


I have worked through the first few layers of issues and eventually figured out that the radiator had multiple leaks... because when the machine first came out of storage and was test run, the space between the fan and radiator was filled with acorns. The fan ground those nuts into the back of the radiator, causing leaks it didn't have when it first came to my property.




Tons of fins in the circular pathway of the fan are mashed inward by up to 3/8" or 1/2" , with tiny holes in the tubes that were not readily visible except for the general areas of coolant wetness






Bummer, because this is about a $900 radiator.


I decided to try and locate the leaks and solder them, so that I could reinstall the radiator and prove the rest of the machine is 100% healthy. Then at a later time I can decide whether to replace the radiator, or whether this might be fine as-is.

The approach I came up with was:

1. Bring the radiator into the shop, vacuum all the debris out
2. Find a way to seal the inlet and outlet
3. Pressurize the radiator
4. Look for leaks visually/audibly, mark the locations
5. Locate smaller leaks with soap+water, mark the locations
6. Prepare/grind and solder each leak
7. Pressurize and test with soap+water
8. Iterate steps 4-7 until all leaks might be fixed
9. Final testing to see if the radiator holds stable pressure for ~12 hours
10. Fix additional small leaks found in #9 if needed

Right out of the gate, there were some dependencies to solve. I don't do much vehicle/radiator work, so I don't have a variety of test plugs to close the inlet/outlet. I could have taken the upper+lower radiator hose off the machine itself, put them on, then just found/made some plug--shaped objects to hoseclamp in the hoses. However, at least one of the radiator hoses has some special components inside (I think stiffeners to keep it from potentially getting drawn flat by the water pump?) and I'd rather leave it attached to the thermostat housing on the machine.

Also, mating surfaces and pressurized components in the sealed system means fewer false positives.

I thought about going to town to see if I could buy test plugs of the right diameters for the inlet/outlet, but then decided to try and make a couple out of hockey pucks.

I had bought a lot of 10 used hockey pucks on ebay back when mounting my air compressor, so that I could turn some mounting pads for it. I chucked one up in the 3-jaw chuck and used a sharp HSS tool to turn it down with an aggressive manual feed rate. Once I got near the desired diameter, I turned a 5 degree taper. This all took maybe 15 minutes?



In my box of 3/8-ish hardware I found a cupped washer that I'm pretty sure came off of a strut mount on my '95 Ford Ranger, this seemed perfect to put inside and draw against, to help encourage the rubber to mushroom outward



The head of the bolt is on the inside, and a nut+washer are on the outside to draw it tight. The center hole in the plug is 1/64 undersized so that it is a snug fit against the unthreaded portion of the 3/8 bolt

I also made a second one for the other port on the radiator, but for that one I used a 1/2" bolt because this puck already had a 3/8+ hole in the middle from a first prototype at making a compressor mounting pad







Now, about pressurizing the system... my neighbor is a retired mechanic and does have a radiator/cooling system pressurizing kit/pump. However, I knew that the leaks in the radiator added up to a significant leakage cross-section. The system would not hold pressure long enough for me to locate the leaks, if I used a hand pump. Really what I wanted was flow through the system, but with pressure regulation so that I would not overpressure the system accidentally as I iteratively sealed the leaks up.

So what I did was took the 3/8 bolt from the first test plug, and drilled a 1/8" hole through the middle. I also turned the threads off the end so it somewhat resembled a hose barb



I then hooked up to it a bit of a mess of random components that I had previously used as part of an improvised smoke testing machine to track down exhaust and exhaust leaks on a previous project:



Shop air connects to a welding flow regulator that has the SCFH gauge on it, and a needle valve for adjusting max flow rate. I just needed to replace the cylinder fitting with a shop air male fitting. The flow regulator is not a pressure regulator, however -- so if you hook it up to a sealed system you will ultimately reach shop air pressure or pop something on the way there. So the flow regulator outlet connects to the inlet of a propane regulator from an old bbq grill. This is set to a fixed 1/2 psi, perfect for leak testing systems safely. The regulator was part of a value-engineered product and has an integral splitter on it for feeding two burners, so one of those has its hose plugged off. The other leads to the hose that attaches to the radiator:




When using this as a smoke tester, this hose goes to a piece of capped pipe that has nichrome wire wrapped around a sock soaked in mineral oil, so that it generates smoke (whose outlet in turn connects to the system under test). Sketchy but I have used it 3-4 times with great success and only one demonstrable fire risk

Now with a source of airflow, I was able to identify 7-8 potential leaks and use a small cutoff wheel (a worn out tiny wheel on a die grinder, I should have gotten the dremel out for precision) to open the hole up a bit and expose a decent surface area for solder to wet





Then used a map gas torch to heat the area and flow solder on. If I had jewelers torches for my OA setup, I would have used that instead because the map and propane torch heads are a huge flame for the 2mm area I am actually trying to heat




Eventually I closed 7 leaks, and the iterative testing brought the flow gauge down to 0 SCFH. Up until the last tiny leak I could find in this approach, the ball was visibly floating -- I could not believe how useful an indicator this was of even the smallest meaningful leaks.
I got the idea for this from a youtube video that showed an actual professional smoke tester, the OTC Leaktamer. It had exactly this style of flow gauge, so I was happy to have a broken/spare regulator in the shop. At some point I should replace this broken high-pressure gauge with one that shows 0-150 psi, the shop air pressures that this really gets used with


Next was spending a few hours straightening fins with a pick. Not to get it perfect, but to open up the cross section which was blocked to airflow - probably 10% of the radiator was blocked, and another 10% was partially obstructed by the bent fins



Here is a before/after of roughly the same area on the radiator:





And overall after:


Lastly, pressure testing to see if this holds pressure. Initial indications are yes, but the pressure did drop slightly overnight. The radiator was still too wet from cleaning for me to find a specific leak, so I am repeating the test in the sun today for it to dry out. Also I saw water around the cap bung this morning on top of the radiator, and found a tiny bit of debris that may have been in the sealing surface of the pressure tester - so fingers crossed that maybe there is no leak






With any luck I'll have a good answer tonight. Worst case there may be a couple tiny leaks remaining, which I hope to identify by water beading tonight

thanks for reading

 

[thomas s]

Nice job, I hope you can save the radiator for what it cost time well spent.

 

[piper184]

Good work using what you had, exactly why we have shops full of cool stuff.

Another air source for high flow/ low pressure is the output from a vacuum cleaner, or an HVLP paint blower. Noisy and annoying but most people have something available where they might not have a regulator/flow gauge like you did.

Nothing to do with machining, but you could possibly do at least some engine testing without a radiator. Rig up a garden hose to the lower radiator hose and second hose for the thermostat housing to just dump the water overboard, no need to recirculate until you get farther along. Think of the garden hose adapters that go on an outboard motor for testing while out of the water.

Best of luck with the rest of the project!

 

[FliesLikeABrick]

Nothing to do with machining, but you could possibly do at least some engine testing without a radiator. Rig up a garden hose to the lower radiator hose and second hose for the thermostat housing to just dump the water overboard, no need to recirculate until you get farther along. Think of the garden hose adapters that go on an outboard motor for testing while out of the water.

Best of luck with the rest of the project!

Thanks for the input -- indeed if the radiator was a complete blocker, that is a great idea. It wouldn't have the nitrite anti-cavitation protection but for a short period of time would be fine I'm sure. It is looking promising that this radiator will be usable at least for testing on the machine, if not long-term. The biggest hurdle that I do not yet have a plan for is load testing. I have thought about building an open-loop water cooled load bank out of copper tubing, but am not thrilled with the probable sketchiness involved. Rentals look expensive, and it seems like a bunch of the usual suspects for rentals require renting their technicians to be involved as well -- as a personal project, that is all probably outside my budget.

I can do some load testing by powering our shop from the generator and turning a bunch of loads on, but that is 240 split-phase and the generator is wired for 3-phase 208. That said, it is rated for 100% imbalanced load, so I should be able to get pretty far this by using two hot legs in place of 240v, using the resistive heating elements in the shop HVAC, machine tools, and electric car charger, and turning on+loading some extra computing equipment. Even moreso if I powered the house at the same time.....

 

[FliesLikeABrick]

The radiator held 15psi all day yesterday without any drops or leaks. The only pressure fluctuations were upwards as it was in the sun and the water inside heated up, and then downwards by the same amount later in the day.

I masked the frame off (not entirely necessary) so I could give a quick flat black prime+paint both for aesthetic improvements, but also to prevent unnecessary corrosion and to help heat emissivity






Ready for reinstallation after work this week

 

[OTmachine]

Good work! Most of those bent fins are from pressure washing, (Bad Idea). I used to do radiators in the service. If you end up going to stop leak, do not use the tar type of sealer. I have had good luck with Alumaseal powdered sealer. It does not clog up things. Kind of works like pepper, (goes to the leak and plugs it).

 

[FliesLikeABrick]

Good work! Most of those bent fins are from pressure washing, (Bad Idea). I used to do radiators in the service. If you end up going to stop leak, do not use the tar type of sealer. I have had good luck with Alumaseal powdered sealer. It does not clog up things. Kind of works like pepper, (goes to the leak and plugs it).

Thanks, yep I 100% knew not to use a pressure washer. In this case the bent fins were in a circular pattern from a few lbs of acorns getting smashed in by the metal fan blades, which is why it was hard enough impact to break some tubes as well

 

[FliesLikeABrick]

Moved this into the yard (950 lbs tongue weight, with this beefcake trailer maybe the whole thing is 10k lbs?) to clean it up and flush the cooling system (easier access to a hose). Then backed it up to the shop...

Reassembled except for some grills/covers/guards, filled with water. Ran for 20 minutes to get up to operating temperature, all looks/sounds/smells good.

Couldn't resist backfeeding the shop through a spare 50 breaker, ran the air compressor and shop A/C, got about 40 amps average on both hot legs that I hooked up.

I have a 100a breaker on the way, then I'll turn on a bunch more load including the car charger and 30a on-demand water heater. If I can get 90 amps sustained load for a while without it skipping a beat, I'll move one of the lines to the 3rd leg and repeat the test.... and maybe call it good there. I also have a quote for renting a 100kw load bank for $500-750 (1 day vs 1 week), if I was determined to prove it fully before selling it.



175F temperature, I'm guessing this would creep up to 190 under moderate-high load. IR thermometer and the air coming out the radiator showed that it was doing its job - entering at around 145F and returning around 110F or so; the exhaust side of the radiator was reading 90-115F in a gradient according to the expected flow



To hook up, I installed a spare 50a 2p breaker temporarily. For the neutral I borrowed a ground lug from one of my 100a subpanels (and left that ground touching some other conductors rather than let it potentially float)



Pretty clean temporary hookup at the other end. I am borrowing this coil of 2awg wire from the previous owners of the genset, will drop the 300lbs coil off to them when I'm 100% done testing



All that really remains now besides putting some more load testing/thermal cycling and the guards/final enclosure pieces back on is ...oil change, replacing the water with a reasonable coolant titration, and a bit of TLC on the trailer wheel bearings and see that the tires have a reasonable pressure in them.

Also possibly the ammeter display for the 3 legs doesn't work, I'll give that a bit of triage -- or my load today was just too small to really register, but I think I should have seen the needle move a bit on two of the three legs.