Inline 6 issues (no heat & high oil pressure)

[holeski]

The motor in my 87 comanche was shot. We swapped one in from my 88 XJ, couldn't have had more then 50-60k miles on it, but sat for some time along with the newer style cooling setup (but that was on even before the motor swap) my issues are these:

 

Runs cold and will not warm up via gage and feel

has little to no cab heat (blows luke warm air but stops blowing at higher speeds)

very poor gas mileage (guessing stock in open loop)

high oil pressure via stock gage upon start up even when in heated garage

blow by from crank case into air filter (worse at high speeds)

 

So the motor itself is not getting hot at all by feel so I don't think its a gage issue. I have changed the thermostat a few times and bench tested them to make sure they work. Could my high presser and no heat be from the same thing? Never did this in the XJ so what am I missing? Could low vacuum some where do this? An air pocket, but I have burped this thing over and over with no change.

[Eagle]

Don't have a clue regarding the heat. It does sound like it isn't getting warm enough to get into closed loop mode, but who knows why? Could be as simple as a stuck thermostat.

 

As to the oil pressure, what's "high" to you? And what weight of oil are you running?

[holeski]

Pegged on the pin 1/4" past 80 on start up. After a few min between 60-80 at ideal and pegged past 80 on the highway. Plus the globs of oil coming out the crank case. Every once and awhile it will drop down the the normal 40 range.

 

I know get a mechanical presser reading, but all the blow by tells me its going to be high. Bad rigs, but only after 50-60K? thought maybe the rings are stuck from stilling so long and thats why. On my 4th thermostat, all bench tested before and after instal. Running 10w30 right now, but doesn't seem to matter what weight I have run as it acts the same may.

[jimoshel]

You should run a compression check.All cylinders should be 120 to 140PSI and within 20PSI of each other.

[holeski]

I plan on doing that and a mechanic oil pressure check today. Alone with new oil and filter. I even have a few extra sensors I might swap in too just to be sure. I'll post up my findings.

[kro10000]

Just for future reference, whenever starting a motor that has been sitting a while, its always a good idea to pull the plugs and shoot some wd40 in the cylinders. That will help break up any rust that may have built up between the rings and cylinder wall so the rings are less likely to seize...

 

I should've done that in the 'stang, 20+ years of sitting and I fired it up into a world of issues. :wall:

[holeski]

I pulled the oil pan, valve covers, intake and all the little stuff off on the stand. Changed ever seal and lubed everything I could. Then treated it like new brake in. Changed the oil and filter at around 500 miles.

 

Yesterday I did just that with some sea-foam. I had it running and it blew all kinds of junk out the tail pipe, idled find but spit and spurred if I stepped on the gas, but now it doesn't want to start at all. turns over a lot better now though. I pulled the plugs which are new and cleaned them up. They looked fouled which I guessed they would be. Next I'll check for spark at the coil and see if I didn't mess something new up it just needs to burn off the sea-foam.

[holeski]

I just ran a compression test. The test was done cold in a garage since I have a non starting issue now also.

 

#1~~~130psi

#2~~~130psi

#3~~~112/117/118psi

#4~~~117/117psi

#5~~~135psi

#6~~~136psi

[jimoshel]

Looks like you have head gasket leaking between 3&4. But those are good figures otherwise.

[holeski]

So what does it mean when the dipstick flies out and smoke comes out of the everywhere when you crank it? Really at this rate I should have left the stock motor in.

[Oizarod115]

sounds like your engine is getting compression into the crankcase which is most likely a head gasket failure, but could be a cracked head. have you verified the super-high oil pressure with a real gauge yet?

[Pete M]

Just for future reference, whenever starting a motor that has been sitting a while, its always a good idea to pull the plugs and shoot some wd40 in the cylinders. That will help break up any rust that may have built up between the rings and cylinder wall so the rings are less likely to seize...

 

Excellent point, except that WD-40 isn't very good at rust break up. A better choice would be a rust penetrant like PB-Blaster. :thumbsup:

[holeski]

No I haven't check the oil pressure, it had just stopped running. After checking every thing over and over I started at square one and reset the motor to TDC. Reset the oil pump, distributor, cap, rooter and plug wires. It must have been timing as it did start this time, ran ok for a few min but then ruff idle and died. I am thinking EGR is giving it a crapy idle now and maybe some vacuum leaks also.

 

I will track that stuff down, see how its running, redo the compression test and oil pressure also.

[holeski]

I think its been running rich, now runs for a short time and starts to buck and miss. Changed cap, rotor, oil and filter and seemed better until I drove it. Changed the temp sensor on the back of the block and not only did that seem to fix the gage reading low but now I magically have heat now too. Messed with the oil pressure sending unit and its reading better for now. Not sure if there is still a pressure issue now or not. I changed the o2 sensor, no change. Disconnected the cat and yup all busted up, BUT isn't blocking flow and runs just the same without it.

 

CPS tests good, but think I might be changing it anyway. Maybe try and change plugs again, week spark, vacuum leak I can't find???

[holeski]

Anyone have a "good" vacuum diagram that shows which lines go where? Not just the ones that lump all the lines in the same group. I don't think its causing this problem, but can't help it.

[holeski]

Head gasket or cracked head. I have coolant coming out the tail pipe. Was the same issue I had before I swapped this motor in. Off course I have to pull the head and verify, but with all the problems I have been having it makes sense. So here is my big question.

 

I have all the parts from a 96 XJ that threw a rod. Can I swap that head and intake on to this block and would it be worth doing?

 

After finding coolant coming from the tail pipe I just pulled the head. No the gasket doesn't really look all that bad. But there was some sort of sand or grit in all the water jackets. Also the cylinder walls look pretty scorn. I hate motor work, I just don't understand everything. At this point I don't feel comfortable just sticking a new gasket on. I think the whole thing needs gone though and tested for cracks.

[holeski]

Pulled the head off since I noticed signs of coolant in the exhaust. I also had low compression on cylinders 3 &4.

#1~~~130psi

#2~~~130psi

#3~~~112/117/118psi

#4~~~117/117psi

#5~~~135psi

#6~~~136psi

 

From highest to lowest there is a 19psi difference. From what I have read thats out of specs..(120-150psi within 30psi of each other)

There are no water jackets on the block other then the front and rear. The head has them all around and the gasket just blocks them up. This seems to be where mine was leaking coolant into the cylinders. There was what seemed to be a grit or same in the water jackets also. The head gasket was pretty thick. I have seen where the JB weld them up to do a HO head swap on the 258, thinking this might be a good idea to do on mine too. Here are some photos, tell me what you all think.

 

 

 

 

 

Top head is the 87, 2680 casting, bottom one the 96, 0630 casting