Diagnosing om617 Toyota Swap Problem
 

Hey folks,
First time posting but used this forum countless times during my swap...thanks for the help.
1986 Toyota 4Runner with a 1985 om617.952 swap.
I’ll cut to the chase. Swap is done, but I’m having overheating and white exhaust smoke issues. White smoke at start which gradually decreases as motor warms up. Idles fine for as long as I want with no cooling issues. However inclines are a huge issue at low and high speeds, white smoke gets bad and engine will rapidly start to heat up. I always lay off before it gets out of control. Smoke gets bad before the engine temp ever gets to 200*f
Overheating issues aside, the white smoke concerns me the most. All the research I’ve done seems to point to a head gasket but there is no noticeable oil in the coolant or milkshake in the oil pan. Again, I’m not as concerned about the overheating since if it is a simple cooling issue I will upgrade the radiator and fan. I’m more worried that the overheating is a product of a head gasket problem.
I’m admittedly not very well versed in diesel motors, so I am wondering what sort of things I can do to narrow down the problem. I love this truck but this has been an absolute nightmare. Basically a paper weight right now since I don’t want to get stranded in the woods with no cell service.
Any suggestions would be greatly appreciated.

If you didn't swap over the MB radiator to go with the diesel engine, I'd say you need to probably take a hard look at that, you need to make sure what ever radiator you have is up to the task. Easiest way is to use the MB radiator, just a matter of fitting that into the truck.

Replace the thermostat and the gasket, they cost about $20 or so. Be sure to check the old and new thermostats in a pan of water on the stove to make sure they open at correct temperature and reach full stroke by correct temperature.

Did you change the injection pump timing at all? Getting the timing off can lead to the white smoke and may also be related to the over heating.

What does the white smoke smell like? Sweet smell = coolant, unburnt diesel smell = injection problem (timing or bad injector(s)).

White smoke + overheating strongly suggests timing problems. Late/retarded injection will cause white acrid smoke (it'll sting your eyes) and have a foul smell. It will also cause excessively high EGT's and overheating from lugging the engine.

If the smoke smells like raw fuel that is an indication of late timing or for some other reason the fuel is being atomized but not burning.

Put a piece of cardboards or board near the exhaust and remove it so you can smell it.

Note that it has happened before that people have acquired Engines that were not in good shape for transplants.

No input beyond what's already been added, smell the smoke to help narrow things down.

Good luck. Went through quite a hassle getting my swap ironed out myself - it was well worth it in the end.

Sounds like a coolant leak into the intake. Smoke on start as it seeps in and puddles overnight. White smoke and overheating as it gets under load and the system pressurizes. Put a cooling system pressure check on it.

Please explain the path the coolant takes to get into the intake on a 617.

The only possible way I can think of is through the head gasket, or a crack in the head. It is not possible to get coolant in the "intake" side of the valves, only the combustion side.

Yup, cracked head, bad gasket or even the block. Not necessarily in the intake manifold per se, but getting in the comvustion chamber. Have seen a Honda with a vertical crack in a cylinder wall years ago. Crack was low enough that the piston still sealed off during high compression and combustion, but picked up coolant on the intake stroke.

Thanks for all the replies.

It's never stung my eyes but it certainly doesn't smell sweet. Definitely smells more like fuel

I will try the cardboard trick...seems like a better idea than sticking my nose in the exhaust pipe.

Thanks. I've referenced many of your previous posts throughout my swap.

I used the MB radiator for the swap. Fitting it in was no fun. Radiator support, meet angle grinder.

Tested the thermostat and is works fine.

Injection timing was adjusted by the previous owner so I have to do some more research to figure out how to mess with that.

That is my concern. Time to do a pressure check

Update 11/19
 

Update here.

I ordered the "engine health test kit" from M-Source. Kit contains compression tester and valve adjustment wrenches, plus a few other things including instructions. I know its cheating to buy the kit but I like the walkthroughs. Just for reference, I could barely change my oil when I bought this truck so I consider it my wrenching classroom.

My goal is to determine if the head gasket is blown before I do anything else.

So first things first, I'm going to do a valve adjustment and then test my engine compression. I'm wondering if my target compression readings will be different than a stock OM617 since I'm using the Toyota starter to turn it over. Either way I'm mostly looking for differences between the cylinders so it shouldn't matter too much.

Then I am going to do a cooling system pressure test. I tried to do it last week and found out there are some hairline cracks in my expansion tank that allowed the pressure to escape, so I ordered a brand new OEM one from Pelican.

Hopefully these tests will help me determine if my HG is toast. I will report back with results.

If they come up negative, I'm going to test the timing on the IP and do an adjustment if necessary.

If all else fails I'm going to try and do a head gasket job. The instructions on this site are pretty detailed so I figure I'll give it a shot.

Mine cranks with the Toyota starter as well, and I get factory compression numbers.

A compression tester or a cooling system pressure tester won't find a coolant to combustion chamber leak.

The _only _ way to definitely test for this is to, remove rad cap, make sure coolant is full, pump about 100 PSI air into a cylinder ( through the glow plug port or injector port with both valves closed ) and look for coolant level to rise or bubbles to appear.

This is the same setup as a cylinder leak down test but you don't need a gauge set. Many times a compression test hose can be used after the check valve is removed.

All other tests including using color changing fluid are pure folly. I base this on 4+ decades and countless engine builds of many brands.

Good to know. Side note, I'm about halfway through your 50 page build thread. Quite a good but long read. Ask me how much work I've gotten done today.

Your insight is very much appreciated. I'll see if I can pull the check valve from my compression tester and rig the shop air into it. I install draft beer systems so I have tubing and hose clamps galore.

In theory (my theory doesn't amount to much), wouldn't running the engine produce the same symptoms? It seems to me combustion gasses would leak into the coolant the same way the shop air would in the procedure you described above. Should I expect to see bubbles or coolant rising by simply running the motor with the expansion tank cap removed?

Given your background, I hope you made a portable " air " supply that attaches to a CO2 tank. I have one when I need to fill many tires / run an impact in a remote location. I even use it with a stapler for house trim / paneling rather than drag out a compressor. One note, since CO2 is a smaller molecule than nitrogen, if you have a leaky tire it will leak faster. ( Nitrogen is a large molecule and makes up about 75% of air. )

I also use CO2 on a MIG welder when welding oh too rusty 1/8" + thick metal. CO2 is a reactive gas and gives the arc lots of dig. The down side it is a slower weld process and makes lots of spatter.

Sort of. Using shop air is a simpler method to find a leak. The problems with a running engine are:

Water expands when heated so you won't know if the rising level is due to expansion or a combustion leak.

The thermostat will cycle compounding the expansion issue.

Many times air hides in a cooling system so, is the air making it's way to the rad cap for purge or a combustion leak?

On some systems have coolant flow near the rad cap, this swirling makes it difficult to tell if the water is slightly rising.

When you use compressed air as a test finding absolute TDC can be difficult especially with a worn motor that has low piston ring tension ( RE Cylinder friction ) . Turn the engine to TDC both valves closed then give it a quick puff of air. Watch the engine pulley and if it turns, rotate the engine the other way a bit farther from your starting point and try again.

Be sure to stay clear of rotating engine parts, 100 PSI is pretty powerful when applied to an engine.

Note, some here will make a big fuss that turning an engine backward will throw the timing chain. Any engine that throws a timing chain on reverse rotation is already worn out and is going to throw a timing chain shortly. Gasoline engines sometimes violently " Diesel " on a hot shut down and can run backwards with great force for 5 or so seconds. This shock load is far worse than a manual reverse rotation.

A gas or diesel engine can spring back slightly when turned off as engines tend to stop when a cylinder is on the compression stroke. The effects of stopping on compression can be evidenced by looking at starter ring gear wear patterns. A 4 cyl will have 2 badly worn places 180* out , a 6 cyl 120* and a 8 cyl 90*.

As you are doing the coolant leak you will get leaks from other places: ( In order of worsening engine condition )

Oil cap / crankcase: Piston ring wear. Some leakage here is normal and gets worse as the engine wears.

Exhaust : Exhaust valve and seat face leakage ( Not valve stem / valve stem seal oil leakage leakage ) This gets worse as the engine wears, some leakage is normal on an older engine and does not affect operation much. Valve clearance less than 0 can cause leakage.

Intake / Air filter: Intake valve. As with the exhaust same causes except the motor is really worn out at this point and power will be decreased.