Sight unseen

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Originally Posted by fullchoke

I'm going to use K-Seal. It is a Napa product. I looked for Steel Seal, but I think I would need to order it through the mail. The directions call for driving it if possible, and idle it for a half hour if not. Since this is a former Gov't vehicle and has no license plate, I will try the idling it routine. The directions don't call for removing the suspected cylinder's spark plug. Only adding product and running it. For all I know more than 1 cylinder is leaking, because 2 plugs looked cleaner than expected. I did drain the coolant and bought a new thermostat. So I plan on leaving the K-Seal in there long term, if it works.
Thanks

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That's sounds like a great plan ~ I only wish you had posted that you flushed the cooling system too ~ if it's not too late DO IT before putting in the K-Seal... I looked down the radiator cap hole into my radiator before & after doing the flush with Prestone Flush Cleaner $5.00 AND I'll be darn it really worked... All of the waterway passage slots were clean & open not like before the flush when they were plugged with crud... It worked..!

The reasons I started using 50/50 premix coolant: (I never did before & never got flu shots either NOW I do both 50/50 & get flu shots)
1) Laziness is the mother of invention ~ it's so easy, just open & pour ~ no farting around mixing stuff or driving around searching for distilled H2O
2) If the only coolant you put in the radiator & OF tank is 50/50 then the cooling system will always be 50/50 mix, nothing more, nothing less..!

Going to post in Fusible Link Now
Hope K-Seal works with 2 bottles or less (Flushing might remove the K-Seal & make the head leak again..? Flush it first...) K-Seal might block off water passages that are partially already blocked with crud & scum.
Best of Luck --
George

I gave it the treatment on the driveway today and the tailpipe cleared up. That is the good part, the bad is steam is coming off the rear of the engine, between the back of the head and the firewall. The top of the transmission looks wet, which I expect that coolant is the cause. I would have let the engine continue to run, but it overheated. The reason for the overheating is probably the root of the problem. Do these engines run hot? There is no fan shroud on the radiator, but it didn't run (at idle) more than 15-20 minutes and the temp outside is about 45. The radiator is tiny, so maybe it needs a shroud, but if I was stuck in traffic on a hot summer day, I think it would overheat quickly. There must be something else to this issue. The radiator was very hot, and when it was cold, water would rise in the radiator when I cranked the starter. I think the water pump is working, it isn't leaking. Possibly a radiator hose is bad internally, but they do look good on the outside. When I shut off the engine and was listening to it rumble. I saw coolant along the edge of the head, I think this truck was hot quite a few times before. Possibly/probably the radiator is clogged, but why is the shroud missing, which leads me to believe the radiator has been removed in the past. I think removing the radiator is my next step unless somebody has a better idea.
When the smoke cleared the engine did run very smooth.
I'm not buying a new head yet, but if I do need to buy one which one of the 3 styles I see mentioned is best?
Any suggestions on where to find a fan shroud besides a wrecking yard? and which years cross to my 1987.
While I was waiting for the engine to heat up, I cleaned out the packed in dirt and pine needles behind the door hinges. The passenger side was packed almost to the top hinge. It looks like a common rust point if that gets left in there too long.

Thanks

I didn't flush it but I wish I did now. Looking in the radiator from the top, it looks clean... no deposits.

I would try the following - check all of the hoses at the back of the engine including the hard line that runs from the back of the water pump. The hard line can develop pin holes in it especially at the elbows and the spots where the hoses clamp onto it. Check head bolt tension? If the head has been off and it wasn't re-torqued after a run in, the bolt torque could be the issue. Check the thermostat - it might be jammed partially closed. And now my favourite - get rid of the factory clutch fan. An electric thermofan is far more efficient than the sketchy mechanical fan. There are too many benefits to running an electric fan not to install one.

Unless the head has a serious crack in it, I doubt you'd be seeing this kind of external coolant leak (not saying it CAN'T happen though) The 4G64 heads had been known to warp so badly from overheating the cams have snapped in half. We've seen posts here enough times to confirm it does happen. This is one of those jobs where you won't know what the issue is until you remove the head (unless it was a bad hose or hard line and you've spotted it) My advice is don't mill a warped head to true it up (especially these heads) I always recommend finding a good machine shop that will bake and press heads straight as cam beds can go out of alignment and cause serious oil pressure and wear issues.

Thanks for the update fullchoke ~
geezer is right you need to verify that none of the coolant lines or hoses are leaking ~ I think OEM trucks came with bronze radiators & no shroud ~ my truck 2.6L Gen1 with original clutch fan original brass Made-in-Japan radiator NO shroud does not overheat even in heavy traffic in Hawaii summer weather ~ the carburetor also has coolant hoses (or does it on Gen2 truck?) is your radiator all bronze or aluminum with plastic tanks? Do Gen2 trucks come with bronze or aluminum radiators? Have you tested the coolant for combustion gases? Did you pressure test the cooling system? BUY & INSTALL A NEW RADIATOR CAP ~ sad, but geezer is right if all is well elsewhere then you should check the head bolts for proper torque ~ when you changed the thermostat did the parts look clean or dirty with crud gunk etc ~ if dirty then your really should flush the cooling system with heater on high heat ~ say geezer, how do you check a radiator to make sure it's not plugged up with dirt..? Any flow testing for that..? In 45°F weather the engine should not overheat ~ there is a way to test the clutch fan to make sure it works ~ google it
Will Say A Prayer
George
P.S. If you check test 'n exhaust all possibilities for the problem and still no fix then you won't feel bad spending a grand or so or more fixing something you simply overlooked ~ as far as getting another head I dunno which one to get except I would get another head with warranty 'n just bolt the sucker on 'n go ~ PLEASE flush the cooling system before installing a new head
Honestly -- Praying
George
P.S. If you get the coolant leaks fixed -- bear in mind that ignition timing too far advanced can cause engine to run hot maybe even overheat ~ someday be sure to use a timing light to check initial timing & advancing of both vacuum and centrifigal advances ~

In an earlier post you mentioned the truck is supposed to have a 2.6L (G54B) with auto. If so and you don't find an external leak, anticipate a replacement head in your future and look for one without jet valves. The G54B head is notorious for cracking even after overheating just once or twice.
Regarding the fan shroud, it's not standard on all trucks. I've only seen them on trucks with A/C, so it may be exclusive to that option. Junk yards will be the best source. Besides other Mits/Ram50 trucks, the shrouds on 1st Gen dodge Raiders and Mits Monteros will fit assuming you have the G54B engine and 23.5" wide radiator. Some minor modifications may be needed so bring a tape measure to assess their applicability and adaptability. The radiators for the 2.0L trucks are almost 5" narrower. I don't know what other vehicles have shrouds that might fit, but other site members may know or have suggestions.

Edit: This site lists as available both the upper and lower portions of the radiator shroud, but you'll pay a tidy sum:
https://www.mitsubishidirectparts.co...ng-system--fan

Best to find out why it's loosing coolant and overheating first. The lack of a shroud isn't the reason it's overheating.

A clogged radiator isn't something that is that easily tested. I've found that plastic/alloy radiators aren't as prone to clogging as bronze/copper (I think it's a metallurgy thing...?:shrug:) but are more prone to the plastic tanks cracking or a tank seal failing. A temperature probe gun will identify cold spots on the radiator cores which would indicate no or low coolant flow. Then there's the epidermal reaction test - touch it and see if you feel if you've got cold spots in it somewhere (only for the brave - or slightly impaired :thumbup: BE WARNED - a radiator at full operating temperature generates enough radiant heat to blister your arm in seconds) The shroud will impact on cooling efficiency but not cause it to overheat as the fan isn't able to draw air through the whole face of the radiator. As xbox pointed out, an overly aggressive engine tune will make it run hot - might not be the root cause but if you have fault A+B and maybe a C in there somewhere then the cumulative effect will be a serious overheating issue. The external coolant leak will be the key in solving this riddle.

*4G64 - is it supposed to have jet valves? (I'm asking because...I don't know :slap:) I know injected G62B and G63B engines had them (FWD) Maybe someone botched a head gasket on it and it has been pinched or folded on a corner - never discount that some monkey with poseable thumbs has been in there before and you've simply been landed the task of undoing their brilliant work...

poseable :lmao: I had to Google, def

I don't think the head has been removed in the recent past, judging by the accumulated dirt covering the head and block.
When the engine was running it looked like the steam leak between the head and firewall was under pressure. The firewall was wet, and so is the transmission below it.
That is good to know about the shroud, because I can see where it would be attached. The fan runs but at idle it doesn't run very fast. I would say it doesn't pull any air through the radiator. Especially since all the while it was idling the hood was up. I have never had overheating with the hood up as an issue with any other vehicle I've owned... that's why I asked if these engines run hot.
The old thermostat had a thin brown coating on it that made me wonder if a sealer was used before, but not what I would call deposits. I have a temp gun somewhere, I will get that involved.
I like the idea of electric fans and made an offer on 2 8" fans on Ebay. Will see where that goes, but I like 2 where I can run 1 automatically and the other manually because the alternator looks small on the truck, and I'm concerned about amp draw.
I think this head has jet valves, but I have not heard of them before and don't know what they do or look like.
Thanks

I went out and ran it at idle for an hour. It didn't over heat, but it was near the high line of the normal range. It was not rising. The temp today was about the same, only a couple degrees cooler. The truck was smoking white again out the tailpipe at start up, but less than before the treatment and that went away once the engine got warm. I never saw any steam at the back of the engine. I put about a pint of water in the radiator and in the reservoir. They were full when I started yesterday and the reservoir overflowed a little when I shut it off yesterday, but was empty at start up today. I don't know why it acted differently today. The only thing I can think of is there was a air lock somewhere yesterday. The truck is nosed downhill some. I'm going to level it out and try it again tomorrow. Using the infrared temp meter.... it showed about 350-360 between 2 and 3 and 3 and 4. About 100 less between 1&2. The oil filter showed 250. Even after an hour of idling my hand would get a damp feeling from the exhaust. I don't normally check this sort of thing, but I don't think that should happen. I did not see smoke. I did not see any coolant leaks today. Your thoughts are appreciated.

H20 is a major component of combustion gas. Temperature difference between front and rear of head is pretty normal for most engines just due to how the oil and water flows through

Repeat your test of today several times or more. At the start of each test, top off the radiator and fill the overflow bottle about half way. Run it until hot then let it sit overnight. Top off as needed before each subsequent test. This should purge any air pockets in the system. If the system is holding, you should quickly reach a point where topping off is no longer necessary. Keep an eye on the temp gauge and for leaks at the back of the engine.

Making GOOD progress fullchoke ~
1) test fan clutch on cold engine spin fan by hand it should not rotate much 2 or 3 revolutions not 8 or 10
2) test fan clutch on hot engine use a rolled up magazine to stop the fan if it stops rotating easily then the clutch is bad if it keeps spinning while trying to stop it then its good
3) Install a new radiator cap
NOTE: auto parts stores carry the fan clutch just bolt on the new one like this: https://youtu.be/S5kuYkcXcUE
GOOD LUCK :thumbup:

The 1st test where it overheated, I started the engine and waited with my hand on the upper hose for some warm water to pass through. It was staying cold. I checked the temp gauge on the dash and it was showing the engine had a temperature on the high side of normal. I checked the lower hose and it was very hot, too hot to handle. The upper hose was only starting to get warm. I took another look at the dash gauge and it was higher. I tried reving the engine some and the gauge moved immediately into the red and I shut it off. It was like the thermostat was in backwards but it was not, and I doubt it would fit anyway. That is when I thought I had an air lock. I will keep repeating the test.

Getting better the radiator top hose should get hot when the stat opens sending hot coolant into the radiator ~ truck sits nose down (?) that can cause trapped air in the cooling system ~ raise the truck front a little above level to help purge air out of the cooling system
DO THIS: https://rustyautos.com/top-radiator-...0has%20opened.

http://www.mightyram50.net/vbulletin...id=26014&stc=1

I ran the test today and the truck calmed down more. Before startup I could see coolant in the radiator, but the reservoir was empty. The engine warmed up and ran smooth. I took a picture of the dash gauge. It climbed slightly after the picture, and after I reved it up it came down slightly. During the 1st test I tried the same thing and it sent the needle into the red immediately and I had to shut it down. I think I only had condensation out the tailpipe at startup and no vapor was noticed at the back of the engine or anywhere else. I feel good about the progress being made. I will do it again tomorrow. Thanks for all the advise.

I'm going to turn the truck around tomorrow so the nose is up a little, since trapped air may still be a factor.

I noticed my truck was running warm the other day. I have been working on cars with my dad since a early age I pulled the cap off carefully to look in the radiator I could see the coolant movement but the coolant wasn’t full. Look inside the radiator to see if you have flow. No flow then you know. Once the thermostat opens you will be able to see the water flowing through the radiator. Not a pro but I hope this helps. Good luck!

I believe I have all of the air purged from the radiator. It is full in the radiator and at the full line when cold in the reservoir. It also runs at the normal temp, so I think I'm good, as I don't see any leaks anywhere or smoke at the tail pipe.
I would say that if you have the cap off your radiator while your engine is running and it is not puking out coolant you are low. Mine will do this as soon as I start the engine when it is cold, even when I was low on coolant. That is before the thermostat opens. Once the thermostat opens there is too much heat and pressure to open it. I just felt the radiator hoses to know it was circulating.
I wish my truck had a manual choke. I'm still learning/searching for a good starting routine. It seems to start and die a lot. The last time I tried pushing the throttle pedal to the floor once and it did start and run without stalling, but I need to try this a few more times. It starts but idles rough in the 1st minute. I can live with that rough cold idle, I don't like cranking it over and over with the start and die routine.
The other thing I find different is if I tap the throttle and rev it, it doesn't immediately fall back to idle. It fall back more slowly than I would expect. All vehicles are different, but wondered if this is a quirk of the carburetion on this truck.
Thanks

An auto choke should work enough to start it off the key and not worry about pumping it or playing with the throttle.
(Tho I think they suck and much prefer a cable choke)
Possibly there's a sticky linkage, the carb needs cleaning out and tuning of mix and idle. Or possibly the autochoke mechanism has worn out (iirc the one in your carb is a bimetallic spring, might have deformed over time, not sure if you can bend them in these carbs, that may be an option)

I would start the truck up and closely watch what the carb is doing

Attachment 26033
Attachment 26034

How to check the choke is operating here

fullchoke, thanks for the feedback & congrats getting your truck running ~ :thumbup:

Member 85Ram50 posted that his truck starts good by pushing the gas pedal WOT once then start ~ seems my truck is starting good that way too on 1st start of a cold engine ~ warm/hot engine I just turn the key which usually works good but sometimes I gradually press the throttle open if it does not start right away, it works ok this way...

The carburetors on these trucks are wired to an ECU nothing simple about it & after 30+ years of use, if not already rebuilt they are most likely way overdue for a rebuild (buying a rebuilt is much faster & easier & most likely cheaper than DIY rebuild ~ been there 'n done that)

The rubber parts begin to fail by cracking splitting getting rotten from old age 'n heat ~ the carb has a few rubber diaphragms & I think they affect pulling off the choke & easing the throttle back to idle (not sure Gen2 my truck is Gen1 Mikuni carb) vacuum can't operate a leaking rotten split cracked diaphragm & the distributor has a vaccum advance diaphragm too (it will most likely be rotten too)

fullchoke, I know you hope that your truck is very low miles which it could be BUT it is still 30+ years aged to perfection just like all the others :(

IMHO: The cheapest, fastest, easiest, smog legal way to get your truck up & running like almost new is bolting on a rebuilt OEM carburetor :thumbup:

IMHO: If legal in your state, modify your truck to run on a genuine Weber carburetor ~ I believe they are mechanical no ECU involved & manual choke ~ however, modifying anything is rarely if ever the fastest simplest cheapest easiest way to do business; especially when rebuilt warrantied parts for your truck are just a phone call away ~ even a repair shop will do the work for you ~ I doubt you can find a shop or be willing to pay a shop the prices they could want to modify your truck from it's OEM configuration...

Anyone (?) am I wrong in thinking that a Weber carburetor will NOT improve MPG beyond what a properly tuned good working order Mikuni will do?

Final Thought: I might do a Weber conversion if operating the vehicle in a no smog law state like (Hawaii :)) but not until I have tried to get it to run properly using original parts & configuration ~ as a last resort I would modify my truck to keep it running just to avoid paying $40,000.00 to $130,000.00 for a new truck here in paradise (Hawaii :shakehead:) I'm old on fixed income, food rent & medicine is more important than any new truck...

Thanks for listening to me rant & blab out loud :P anxious to know your decisions fullchoke, others will chime in to help you as well...
Aloha -- George

Since completing a Weber swap on my '87 2.6L, I'm getting better fuel economy and performance than the stock Mikuni ever gave me, even when I first bought the truck in supposedly good tune (seller had just passed emissions prior to sale). Once I got the jetting right, the Weber also passed emissions just fine.

The Weber 32/36 DG-series -- and perhaps to a somewhat lesser degree the older DF-series the DG was derived from in mirror image -- is a relatively recent design (as carbs go) engineered for inherent efficiency and low emissions as-is, whereas the Mikuni was based on a relatively ancient design originally meant for performance, to which they kludged in a bunch of mods and electronically controlled gizmos to help it do better with efficiency and emissions.

Mind you, the related Weber 38 DGAS won't be as efficient, simply because it's got larger barrels that both open simultaneously, whereas the 32/36 is progressive, using only the more efficient 32mm primary barrel alone until you really step on it to open the 36mm secondary barrel. The 38 really only offers a significant performance advantage at high RPM with a tuned/built engine that can take advantage of the freer breathing.

Would an as-new Mikuni and ECU and all their related gizmos run as efficiently as the Weber or better? Maybe, but it may also be a tall order expecting all of that to maintain "as-new" functionality for the long haul. The Weber eliminates a LOT of complexity and potential failure points while delivering as good if not better emissions, economy and performance. If your area doesn't require emissions inspection with all original-spec equipment (e.g., mine only checks for a cat, good gas cap, and secondary air induction), I'd say doing the Weber swap is a no-brainer.

Just make sure you get a genuine Weber! Look for a rough/dull finish (not smooth/shiny), Weber name/logo and "Made in Spain" cast right into the body (not a decal or ink stamp), and usually a translucent off-white electric choke cover (not black, tho' some used carbs can have these swapped or upgraded from a water choke, so it's not a dead giveaway).

An update on my little truck.... I'm no longer adding coolant after a warm up, so I believe all the air has been purged. It also doesn't overheat, so it must have been the trapped air. It doesn't smoke when it's warmed up, but I think it may when it is 1st started. It seems like there is more than the normal condensation, and there is a faint smell like before the sealer was used. I haven't taken it out on the road yet, but I have been to the u-pull-it, and picked up a good tailgate handle, a hood cable, for the dangling one with the broken mount. I also got a glove box latch from a 94 Mighty Max, but that doesn't fit. I also got a fan shroud from the mighty max it was a V6. It looks like it will fit, but I don't think I will use it unless I need it. I don't like the window crank handles on my truck. They don't have the rotating portion on the handle and think it could have been left off, being the base model is what I have. I'm wondering if there was a cover on the trans hump under the dash on the base model. It looks like something is missing there with the brackets uncovered. I forgot to get the one that was on the truck in the wrecking yard. It had a bed liner too, that I'm considering. I looked at the date on my truck and it was delivered to the USAF 09/86. When I get some sunny weather I'll take some pictures of it. I think it's name in the US park service was "Huck". I hope I heard them right.lol
If I do decide to change out the carb, the Weber sounds like the way to go. Thanks

Hello fullchoke :thumbup: