OIL COOLER? Should there be one? Oil leak maybe from oil filter housing bolts - GEN1

[unashi]

Hi gang - first time post. I recently picked up a 1990 Montero LS (MT) - with fresh rebuilt engine. HUGE disclaimer - I'm not super savvy with engines or cars in general.
I have a small oil leak which I thought was coming from the Oil Cooler Bypass Valve. So I swapped that out with a new one - but still have the leak. Today I think I traced it to one or both of the silver bolts that are just above the bronze bypass valve on the oil filter housing. I believe this is the return spot for the oil cooler lines (but I guess I don't have one?) Should there be one? After some research I found part MB033054 - gaskets that might be the right ones for the silver bolts. I feel like a goof asking if I'm supposed to have an oil cooler, but it doesn't make sense to me why I would have a oil cooler bypass valve and no oil cooler??

Thanks in advance and appreciate everyone's discussions/help on this forum - wife and I had a 1990 gen1 20 years ago and missed it so much we finally found another. Super stoked.

 

[Montynv]

I have a 91 LS LWB, it has an oil cooler. I would think most if not all LS V6 models would have come with a factory oil cooler. I had a leak showing the same spot. It turned out to be an oil cooler line. I have since replaced both lines with new OEM lines. So far so good, but would like to hear if the gasket solves your leak.

 

[unashi]

I have a 91 LS LWB, it has an oil cooler. I would think most if not all LS V6 models would have come with a factory oil cooler. I had a leak showing the same spot. It turned out to be an oil cooler line. I have since replaced both lines with new OEM lines. So far so good, but would like to hear if the gasket solves your leak.

Thanks so much for the response! Yeah - someone must have pulled it out a while back... hoping I can either find a used OEM or maybe aftermarket. I torqued down the bolts that are currently there and that seems to be holding for now, but time will tell. I may swap out with the gasket if the leak persists. I'm taking it to the dealer soon to see what they think on the oil cooler.

 

[unashi]

**UPDATE** OK I'm a goofball - the oil cooler is definitely there. Just missing the lines. Capped off at the cooler and the oil filter housing - not sure why someone did it, but what is interesting is that the temp is holding at the halfway mark on the temp gauge without the oil cooler. From what I've heard from folks that actually might be running a bit hot. Looks like some lines are in order

 

[plh]

Thanks so much for the response! Yeah - someone must have pulled it out a while back... hoping I can either find a used OEM or maybe aftermarket. I torqued down the bolts that are currently there and that seems to be holding for now, but time will tell. I may swap out with the gasket if the leak persists. I'm taking it to the dealer soon to see what they think on the oil cooler.

It would be a rare dealer that knows anything about these vehicles. Its 30 years old! Most dealer techs are about that age, they certainly did not have hands on experience while in diapers

Almost all Mitsubishi dealers closed up shop and fired their staff during the 2008 global financial crisis. Staff moved on to different brands of cars or out of the sector completely. Those dealers that are around now are mostly new businesses opened after 2010.

 

[MummifiedCircuitry]

**UPDATE** OK I'm a goofball - the oil cooler is definitely there. Just missing the lines. Capped off at the cooler and the oil filter housing - not sure why someone did it, but what is interesting is that the temp is holding at the halfway mark on the temp gauge without the oil cooler. From what I've heard from folks that actually might be running a bit hot. Looks like some lines are in order

Probably for the same reason I looped the oil cooler lines on my Gen2, new ones were $250 or so for the pair when I checked.

 

[unashi]

It would be a rare dealer that knows anything about these vehicles. Its 30 years old! Most dealer techs are about that age, they certainly did not have hands on experience while in diapers

Almost all Mitsubishi dealers closed up shop and fired their staff during the 2008 global financial crisis. Staff moved on to different brands of cars or out of the sector completely. Those dealers that are around now are mostly new businesses opened after 2010.

Hi - thanks for the intel - I'll tread carefully. Thankfully the local dealer I'm working with has a few guys who are montero fanatics and they touch gen1s from time to time. And yes...they are young! hahah

 

[airbats801]

If you wanna cheap upgrade, the sr montero oil cooler is about twice the size of the non sr oil cooler. Should be close to a bolt in. Something to consider. I've grabbed a few in the jyard over the years, just make sure you clean them really good

 

[unashi]

If you wanna cheap upgrade, the sr montero oil cooler is about twice the size of the non sr oil cooler. Should be close to a bolt in. Something to consider. I've grabbed a few in the jyard over the years, just make sure you clean them really good

Thank you - good advice! I'll keep ya'll posted on how it all pans out!!

 

[Montynv]

Fyi...the gen 1 oil cooler lines are still available thru the dealer. Everything you need is available, lines/ brackets/ bango nuts and correct washers.

 

[Montynv]

Also you will need your VIN and the dealer can print up the parts diagram showing the needed parts and numbers. You can also download Mitsubishi ASA and do the samething. Than search the web with the part numbers. I just replaced my lines a few months ago.

 

[CharlieNorth]

I am curious what was done to the thermovar when they blocked off the cooler? The oil has to route through the housing somehow.

 

[JohnnyBfromPeoria]

Charlie, that's a good point, and I don't know. However, there are actual factory block offs for those two fittings, and those in the picture are not it. Looks like somebody found something that fits, however. All of the early V-6 models used the same oil filter housing with the fittings for the oil cooler but some Monteros don't have a cooler and have the block off bolts installed instead. They would use the same "special" washers, the stock ones being copper with the rubber center section, but others have said regular copper washers work just as well/better. Having said that, I doubt the temperature of the oil would reflect in your coolant temperature much, so that's not telling you much. You can have new lines made by a hydraulic hose shop if you take the old lines in and they reuse the ends. You could say to heck with it and run full synthetic oil and not worry about it as long as you're not towing and keep it out of overdrive on long hill climbs - and use low range off road, IMHO. You can look at the parts schematic at Partsouq for the breakdown as well.

 

[unashi]

Hi all..thanks for all the info and tips - our Monty is still in the shop (ugh), seems like the oil cooler lines are taking a bit longer than expected for delivery. I'll keep you posted. On the topic of Temperature - mine stays pretty much a hair less than center, and moves a hair above center on the highway. I was hoping that these lines would help with this, (I saw your comment Johnny) as so many have stated on various forums that normal operating temp is generally down in the lower quadrant of the gauge.
While in the shop we are also taking care of the IACV, full Transmission service and some other small items. I just purchased a MAF Sensor, which I'll try to do myself. Unsure if the thermostat is OEM (195) or aftermarket (180) ..... not sure if that would have a huge impact on temp reading at the gauge?

 

[plh]

Install gauges with numbers if you really want to know the temperature.