Compression test/leak Down

[85Ram50]

Edit- Forgot to mention this is the G63B 2.0 motor. Anyone who knows got any feedback about those numbers? for some reason they won't stay lined up as a column under where i posted Cyl1-4 when I click to post.

So I've got all the steering suspension and brakes updated, the interior is civilized enough it isn't a chore to make myself drive it. I have begun trying to figure out why I have crap MPG (low200's per tank) and maybe why it likes to increase the idle as it gets hotter.
I still have a lot of now superfluous wires on it.
I have done a dry/wet compression test and a cylinder leak down test. Here are the numbers

Compression Cyl 1 Cyl 2 Cyl 3 Cyl 4

Dry 157 152 155 170
Wet 170 170 165 167

Leak Down 25% 27% 28% 27%

I know the leak down is good as its all the same. But Cylinder 4 is weird for having a lower pressure wet than dry. Plus 1,2,3, are all 20 psi lower than 4 dry. The plugs looked used but not overly so. I brushed them off when I put them back in and it started fine.
Oh I only had to disconnect the power wire to the fuel pump from the oil pressure switch to get away with out pouring gas through the system. And I used the paper over the plug hole method if finding the compression stroke for each cylinder. Then a screw driver in until it stopped coming up and felt like it was gonna start down.
The only thing that is off which I have never mentioned before even though its been going on for years is that it sometimes seems to catch when it is starting as if there is something dry in the motor not wanting to slide by. Could be a tired starter. It is used.

[85Ram50]

OK today I tested the oil pressure. It started up cold at 66psi. I let it warm up and i came back to check and it was 18 psi. What is the issue??? AFAIK it is supposed to be north of 48psi when warmed up. It goes up and down when I rev the motor just as quickly as I rev it. Then sits at 18psi at idle.

Note: I did not know about the balancer belt which apparently runs the oil pump. It broke about a year after I bought it on an incline with a load I heard a big pop. It kept running so I didn't do anything about it. Never got an oil pressure light. When the head blew 11 years later, 5 years ago that is when I found out about that belt and honestly its only yesterday as I read up before doing the test this morning that I found out it drove the oil pump.

[geezer101]

Either the oil pump housing is chewed out or the bearings have failed. These engines do have an inherent oil pressure issues in regards to oil flow to #1 cylinder, main journal and through the head. If the engine is starved of oil (or the engine is simply worn out), it can potentially do catastrophic damage from loss of oil pressure. Biggest culprit for oil pressure loss is the balance shaft bearings being worn out past their serviceable life. Doing a balance shaft delete solves a couple of potential problems but that's a different matter. Don't know if you've done an oil flush yet but that may help. I did a write up on my method and everyone so far has given positive feedback on results.

[85Ram50]

I did that flush with diesel around when I put the new Weber in. So if its worn out do I replace the pump or what? RA only seems to have parts of the oil pump system.

[geezer101]

You can buy whole pump assemblies. Make sure you get the right one as there are a few variations. It has to come off a 6 bolt engine but IIRC there is a later 6 bolt oil pump with bigger gears to improve oil pressure (someone will verify that...)

[85Ram50]

How do I determine which oil pump I need? 1985 G63B 2.0 (Why doesn't vehicle display when one is logged in but does when one isn't?)

Found this on ebay, it lists as for the 2.6 but says its compatible with the 2.0
https://www.ebay.com/itm/Oil-Pump-for-Plymouth-Voyager-84-87-L4-2-6Lts-SOHC-8V/283443247417?hash=item41fe88b939%3Ag%3AqqUAAOSwz-ldHRwu&fits=Year%3A1985%7CModel%3ARam+50%7CSubmodel%3ACus tom%7CEngine+-+Liter_Display%3A2.0L%7CMake%3ADodge%7CTrim%3ACust om+Standard+Cab+Pickup+2-Door%7CEngine%3A2.0L+1995CC+122Cu.+In.+l4+GAS+SOHC +Naturally+Aspirated

[geezer101]

No. 2.6 and 2.0 are completely different engines. That is definitely a 2.6 pump. This is a listing for a complete oil pump housing for a 2.0 -

https://www.ebay.com/itm/Oil-Pump-For-1983-1989-Mitsubishi-Mighty-Max-2-0L-4-Cyl-1985-1984-1986-X164VB/153300555164?hash=item23b16cd59c:g:OA0AAOSwR75dP9Y F

[85Ram50]

Where is the moving part that pumps on that Geez? Or do I have to buy other parts? I'm guessing but I expect my existing parts are not going to be worth reusing.

[geezer101]

How the oil pump on a G63B works - the balance shaft passes through the back of the oil pump gear housing and locks into the driven gear while the driving gear has the timing belt sprocket on it and is mounted from the front. The actual gear housing is on the back of the pump assembly and can't be accessed while the pump is installed on the engine (hope that didn't sound like gibberish)

[85Ram50]

I somehow have the idea the 4G63 is teh same as a G63B. Am I correct? I ask because I found a vid of a guy taking the oil pump and the balance bars out. in the next vid he shows how to install a delete kit but it cuts off once he gets to installing a bearing in the hole on the right side of the engine.

What search term should I use to get a balance bar delete kit for this motor?

I'm still debating on whether I should just tough it out until I save enough for a crate motor instead of rebuilding this one one broken part at a time.

[claych]

I have done a dry/wet compression test and a cylinder leak down test. Here are the numbers
Compression Cyl 1 Cyl 2 Cyl 3 Cyl 4
Dry 157 152 155 170
Wet 170 170 165 167

Leak Down 25% 27% 28% 27%

I know the leak down is good as its all the same.

Yes the leakdown is excellent , Edit Most Excellent, for a worn engine.

???100 psi shop air ???

[85Ram50]

Shop air was about 90psi.

[geezer101]

There are kits available. But I'd be cautious. The component you need to keep your eye on is the oil pump shaft delete. There are cheap kits that have a shaft without the oil journal in it and these will wear out your pump and cause oil pressure drop out. The kits on ebay for 4G63 engines are either a major rip off or have the dud oil pump shaft. All you need is the stub oil pump shaft and the block off cap. Remove the bearings in both side shaft journals and rotate them so the oil ports are blocked. This should be a cheap enough exercise (here is the part you will need (https://www.ebay.com/itm/MD098626-Genuine-Mitsubishi-SHAFT-OIL-PUMP-DRIVEN-GEAR/182717635081?epid=1511262063&hash=item2a8ad1da09:g:7UcAAOSwGrVcbZPr)) the other part is a seal cap that replaces the front seal on the other counter balance shaft (do not do something like try to knock a freeze plug into it to seal it off)

[claych]

Shop air was about 90psi.

So, subtract 10% from your readings assuming the gauge
used was accurate.
--- Lack of mileage ---
With respects what were You expecting from a 122 cubic inch sohc 8v carb dist fired 4 cyl 34 year old engine ???

[85Ram50]

Thanks Geez. that is what the guy doing it mentioned too. He seems to think that is a stock stubby shaft from a Mirage. I guess he was getting to the block the oil passages with the new bearing when his camera dropped the pic. I noticed he posted in 2010. I assume I was correct in thinking the 4g63 is the same since you did not mention it.

The leak down tester said to set it at about 90psi. I am looking for reasons to explain poor MPG on a motor with only about 112K original miles on it. I am also trying to figure out why the Idle keeps increasing as it warms up. The only factor I have nailed down is the heat being a part of the issue which is why I have a 14mm spacer under the recently new K610 kit 32/36 Weber.

[geezer101]

That is the shaft off a 4G15 engine IIRC. I have the shaft and the seal cap waiting for the shaft delete myself. The idle creeping up is a strange issue. Normally the heat would do the opposite...

[85Ram50]

I like the kit this guy had. This is the second vid that cuts off early https://www.youtube.com/watch?v=dstUTb_1z8I
Haven't found one with that castle nut thing in them yet.

[geezer101]

The 'castle' plug is on the 4G63 twin cam engine. DSM guys have struggled with oil leaks after messing with them. The SOHC G63B cap is fine and is probably more reliable in that aspect.

[85Ram50]

Good to know Geezer. It ran nice today except for the revving. full tank 30 miles the gauge hasn't moved down yet. ?? Maybe its happy I was nice to it :)
It is going to cool off and rain again here. We should get another week of heat in a bit. When it does I am going to test a theory and disconnect the vacuum advance from the Dist after the idle starts increasing to see what happens.

EDIT- I was surfing looking for a G63B Balance Shaft Delete Kit and came across a link to someone on here in 2013. LSR mike chimed in with this gem of a page http://www.vfaq.com/mods/balance-shafts.html

[geezer101]

The JB weld and freeze plug method of deleting the counter balance shaft is a disaster waiting to happen (if the thing expands it could crack and you'd have oil pouring out all over the place). Use the cap seal thingy. Everything else I agree with in that link. You do not need to align the timing marks in the oil pump gears after the balance shaft delete but I'd do it because I'm OCD lololol. That link should have it's own thread in the performance mods section as a direct reference. There are all kinds of opinions on whether or not this mod is a good idea. My G63B engine was trash from the factory (possibly one of the worst alloy head castings I have ever seen...), but that being said the reciprocating parts were within 1-2 grams in weight of each other so IMO there is very little of scope to improve bottom end balance.

[85Ram50]

I did not read it all as I did not see the JB weld part. I found it interesting that all the parts are available as individual parts. It looks like he is doing a lot more than I thought was necessary from that YT vid.