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Discussion Starter #1
before i begin, to everyone that has been helping me get through the issues my samurai has been giving me, thank you.

I can't be sure if i have a leak in my head gasket. the only symptom i'm seeing is a small amount of oil/water mix on the inside of my oil cap. i only see the "milkshake oil" when the engine hasn't had time to heat up yet. once i reach operating temp, all i see on the cap is oil. there are no other symptoms that would point to a blown head gasket. not overheating, no knock, no loss in compression. is there something else that could be getting water in the oil? or is this a leak in the gasket that just isn't big enough to cause any of the other symptoms?
 

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Discussion Starter #2
AHHHHHHHHHHHHHHHHH!!!!!! driving down the highway last night, i started losing power fast. i limped my way to a parking lot and my folks were kind enough to tow me down to the shop i do my work at. she's running really rough, the engine will idle, but misfires a little while idling, and misfires a lot when under load. she's got good spark. i did a compression test and got these numbers:

cylinder psi
1 155
2 150
3 150
4 155

if i'm not mistaken, those numbers are a lot lower than they should be, and i need a new head gasket. but i don't have any other symptoms. the oil/water mix isn't showing up on my oil cap anymore. and, the engine isn't getting anywhere near overheating. i need some insight.
 

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if you don't have imulsion in your oil or in your coolant then you may not have a head gasket issue. The compression could be off from the valve timing being off (slipped a tooth on the timing belt) could be worn rings as well. that would cause some extra pressure in the crank case and the condensation that forms could cause an emulsified appearance to oil on the cap or in the breather tube.

since all the numbers seem to be off by the same increment, i'm betting on valve timing
 

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Discussion Starter #5
I checked the timing belt, the marks are right where they should be after turning the crank by hand two rotations. when i replaced the busted rocker arm, i when through all the valves and adjustd the lashing. could it be i just didn't tighten the lockdown nuts enough and now my lashing is way off on a few valves?
 

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Sounds like the compression is a littlelow but that is not low enough to cause much of a drivablility problem. It could be the valve timeing but I would lean more towards a ignition problem or fuel problem. A misfire under load general points to an ignition problem,:) but could also be you are loosing fuel pressure. Your head gasket is not bad that is just normal condensation in oil cap.
 

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Unless the valve lash was set incorrectly on all of the valves you wouldn't have that consistant a compression loss on every cylender from a couple lock down nuts working loose. When I set my valve lash according to the specs, the mechanic working on my engine 2 weeks later told me my valve lash was off. He told me it looked like someone set all of them at the same increment out of spec. So either my feeler gauge is off, or I'm useing improper technique.

Like Camisami said, the compression isn't up to par, but you should still be able to drive it like that and you shouldn't have a rough skipping idle from it being down 20 or 30psi. The ignition is the easiest part to inspect and I'd rule that out first before I started tackling fuel delivery.
 

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Discussion Starter #8
timing's where it should be, and i've got good spark on all four plugs. i think ignition has effectively been ruled out.
 

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on 94 models they used the throttle body injector. Maybe you have a faulty temperature sender. It helps regulate the mixture, which could be the cause of your power loss. Check fuel pump and make sure it's operating at the correct pressure and that it's pumping fuel.
 

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Discussion Starter #10
do you mean the intake temp sensor? i just replaced it about 3000 miles ago, just before i discovered the broken rocker arm. because the check engine light would come on every once in a while and that was the only error code i got.

i know the pump is working, the engine is getting fuel. and judjing by the smell of the exhaust, it's actually burning rich.
 

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if it's running rich make sure it's not starving for air. Check air filter and check to make sure the ambient air pressure sensor is working (altitude sensor/compensator) Also check for backpressure if you can. should be about 2 or 3 PSI before the cat at idle.
 

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Discussion Starter #12
i can't find anything in my repair manual about any sensor to deal with pressure besides manifold and fuel. where is that sensor located? i'm sure my backpressure is a little low, the cat rusted off sometime ago and was replaced with a piece of pipe.
 

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check for bananna's in the tailpipe


my bad on the atmospheric pressure sensor. On the TBI models its the manifold air pressure sensor. MAP sensor.
 

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Discussion Starter #14
no bananas, but i did find a potato. and the the blinker fluid is good. :)

i've gotta pickup a vacuum pump and test the sensor next time i have time to get under the hood.
 

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X2 on the MAP sensor. If it is running rich that is very possible. If you can borrow someones that would be agreat way to test it.
 

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Discussion Starter #16
i may have to buy a vacuum pump, but my friends and i are a huge group of nerds so i won't have any trouble finding a multimeter to borrow.
 

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since all the numbers seem to be off by the same increment, i'm betting on valve timing
Like Baratacus, I'm leaning towards valve timing being off, the timing marks might be right where they should, but is the crankshaft pulley where it should be?

On the larger G16 engines there is a known problem with the keyway in the nose of the crankshaft becoming damaged and causing timing problems, the G13 uses the exact same design, and the problem is theoretically possible.

A leakdown test might help identify the problem area - or - you could check to see if TDC on the pistons coincides with the TDC marks on the pulleys.
 

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I would ck the valve timing, but those numbers for compression are really probably good. I have never done a compression test on a Sammi but I hve done many on different types of engines and those are right on the money for engines from that time frame[moderate compression ratio]. Newer high compression engines [ and eng from the 60s] read a little higher but the rule of thumb is between 120psi and 170psi with no cyl more than 10% off from the others. IF you add a little tranny fluid to each cyl[jus a little] and retest it should be slightly higher[5-10psi] - if it is much higher you know the rings arenot sealing well.
 

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Discussion Starter #19
i definitely planned on redoing the compression test similar to that. I was always told to pour a tablespoon of regular oil down the plug hole, but it would just be splitting hairs to debate which fluid to use.

when i pulled the timing cover off, i put the crank sprocket at TDC and the cam sprocket lined up perfectly on TDC. so i think it's safe to say the belt did not slip a tooth. going off of fordem's input, would i be able to feel some play in the crank sprocket if the keyway was damaged? or would i have to remove the sprocket and visually inspect it?
 

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I would ck the valve timing, but those numbers for compression are really probably good.
A statement has already been made (third post) on on those numbers, and they are low, in fact well below what the FSM considers acceptable. Having said that, in my experience these engines will run surpringsly well (smooth, no missing) with low compression (~100psi), although they will be down on power.

when i pulled the timing cover off, i put the crank sprocket at TDC and the cam sprocket lined up perfectly on TDC. so i think it's safe to say the belt did not slip a tooth. going off of fordem's input, would i be able to feel some play in the crank sprocket if the keyway was damaged? or would i have to remove the sprocket and visually inspect it?
There would not necessarily be play, it would depend on how loose the crank bolt is - to see it you will need to remove the sprocket, but before you do that I would try sticking a drinking straw (or similar) through a plug hole and slowly turning the engine whilst feeling the piston movement with the straw, to detect when the piston is at TDC.

The real question is this - if you know the history of the engine - has that bolt been removed at any time. If it hasn't then a worn keyway should not be an issue.

A question - some of these motors had a timing inspection plate at the bellhousing end - if yours has one, you can also check TDC there.
 
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