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Discussion Starter · #1 ·
Hi all, my 01' SRW started making coolant disappear about a month ago, but here lately it's gotten worse. It has been using about a gallon every 40 miles. It's not leaking on the ground, it wasn't in the oil until recently, and I can't tell if it's burning coolant. I just put a new water pump in about 10K miles ago, and the front cover didn't look bad. There is not fuel or oil in the overflow tank. I have been checking the oil every time I start it and aside from being VERY black it was OK. This last time it had the oily-white sludge on the upper half of the dipstick, so now it is parked and awaiting a compression test. I'm thinking maybe a bad head gasket. Does that seem logical?
 

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Before you tear your engine apart, rebuild your oil cooler. Head gasket issues in the 7.3 are extremely rare. Oil cooler internal leaks are inevitable.


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Discussion Starter · #3 ·
OK, thanks RT. I was figuring on changing it anyway if I had to pull the heads. I could just change it first, but I thought that an oil cooler leak would cross contaminate both ways? And I don't think that seven gallons of antifreeze got into my oil before I noticed it. That would have made a giant mess of the oil after the first gallon.
 

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O-rings can be funny things. If it was a fixed diameter hole, you would expect oil in the cooling system while the engine was running and coolant in the oil when it was turned off. Sometimes an o-ring will only leak one way - like a trap door. There are hundreds of examples of people with leaking oil coolers only mixing oil in the coolant or the other way around. There are probably less than a half dozen posts about head gaskets blowing and most of those guys were running heavily modded trucks.
 

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I only know of one stockish truck that blew a head gasket. It's pretty dang rare on a 7.3
 

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Discussion Starter · #6 · (Edited)
That's good to hear, I will get one ordered from International on Monday. Thanks for the input guys. I will post back when I get it replaced,or if the compression test shows something crazy.
 

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Discussion Starter · #7 ·
Well, International wanted way more than I wanted to pay for the oil cooler, so I called up Tousey Ford. I am going to order the oil cooler and some new injector o-rings. While I was warming it up for the compression test I noticed that it had oil running out from around the base of several of the injectors.

Here are the results of the compression test:

Cyl#1 - 320#
#2 - 325#
#3 - 325#
#4 - 340#
#5 - 315#
#6 - 325#
#7 - 290#
#8 - 295#

The whole engine seems low, but I am concerned about the two back cylinders. They are within 20% so I'm going to assume they are ok for the moment. I was going to do the test cold because I didn't want to run it with coolant in the oil, but I couldn't get more than 250# on any cylinder. So I ran it until the engine temp gauge was up to the normal temp and my oil temp gauge was at 180.
 

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Discussion Starter · #9 ·
Thanks RT. I will get parts ordered and post back when I get them installed. What are your thoughts on the CT results?
 

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Usually, when you see such consistent results that are that far from normal, its a gauge issue or a technique issue. For example, someone who has weak batteries or is only doing one hole at a time - leaving all the other glow plugs in place. Or on a gasser, someone who doesn't open the throttle and choke.

To get a good compression reading, you need both batteries charged (and I hook up jumper cables from my truck to the other person's truck so we keep the voltage up), all the glow plugs have to be out, and the engine needs to cycle the same number of times each test. I use ten revolutions as my standard. If you come up with a weak number, standard protocol is to shoot a little oil into the cylinder and try again. If it climbs substantially, you can usually blame the rings. If you bring that cylinder to top dead center and apply air pressure (leak down test) you can usually hear where the issue is (hissing through the intake, exhaust, or up through the valve cover) but with the exception of rings on a high mileage (think 750,000+) engine, the consistency between the holes is the curious finding here.
 

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Discussion Starter · #11 ·
Thanks RT. I didn't charge both batteries before I started, but I did charge one battery for about 4 hours. And I had a battery charger on the other battery while I was getting the valve covers off and glow plugs out, so maybe 2 hours, as well as during the test. I did pull all 8 glow plugs out, but as far as counting the revolutions, I just went by ear and by my gauge so consistency may be an issue.

As far as putting oil in the cylinders, I don't know how that didn't dawn on me, but I will do that when I replace the injector o-rings.
 

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When you pull the injectors, oil and diesel will drop down into the cylinder anyway. I wouldn't add any additional oil. Since you're going to be pulling the glow plugs to clear the oil after you pull the injectors anyway, I'd spin it a few times with the glow plugs out and then re-do the compression test. That will allow the high pressure oil rail to clear air while you're doing the test. Kill two birds with one stone.
 

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Discussion Starter · #13 ·
Thanks RT. I should have my parts in on Thursday and I will post back when I get it all put together.
 

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Hate to interrupt but am curious. What's your intake look like? C.ean dirty? What's your turbo compressor wheel look like.
RT. mentioned the importance of batteries being up to trying to achieve consistent spinning over speed. This us exactly why I do cranking and a running dynamic test. This will give you a good consistent speed, takes excessive valve to stem clearance that usually only causes sealing issues once that valve really starts getting pushed back and forth fast,fluids have
burned off that can lead to erroneous readings and metal warmed. This gives me a real time idle speed compression.
 

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Discussion Starter · #15 ·
Dieselnick- The intake is pretty clean. I have seen it pretty dirty in the past, which is why I did away with the factory intake. I just noticed that I don't have that in my sig, but I have an AEM intake on this pickup. The compressor wheel is in great shape. I have the intake off at the moment so I can check it again when I go to the shop in the morning. But I spun it and checked the free play in the bearing when I pulled the intake for the compression test. I'm assuming you are talking about a cutout test or contribution test as running dynamic testing?
 

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Dieselnick- The intake is pretty clean. I have seen it pretty dirty in the past, which is why I did away with the factory intake. I just noticed that I don't have that in my sig, but I have an AEM intake on this pickup. The compressor wheel is in great shape. I have the intake off at the moment so I can check it again when I go to the shop in the morning. But I spun it and checked the free play in the bearing when I pulled the intake for the compression test. I'm assuming you are talking about a cutout test or contribution test as running dynamic testing?
No, Nick is talking about a compression test with the vehicle running. Check out this video at about the 4 min mark.

 

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Discussion Starter · #17 ·
Wow, I have never heard of doing a compression test with the engine running. It looks like he was leaving the injectors plugged in to do that test. Should I be unhooking them to do that? I'm assuming that he can cutout individual cylinders with his computer.

Compared to the compressor housing in that video, mine is brand new!
 

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Discussion Starter · #18 · (Edited)
Well, I got it all put together last night and it runs like a brand new pickup now. I'm going to change the oil again today and I will post back when I take it to town to see how it does.

On edit: I did try to do a running compression test but I guess it was too much heat. On cylinder #2 the readings were 510# running and 325# cranking. When I pulled the adapter out of the glow plug hole I noticed a bubble in the rubber, and when I tried to do #4 the adapter blew at about 150#.
 

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Discussion Starter · #19 ·
Well, I have put about 100 miles on the pickup since working on it, and it is still using coolant. So far I have added about a half-gallon for three days in a row. I topped it off yesterday morning, and when I got to where I was going (about 30 miles) the coolant level was under the "Min Cold" mark on the tank by almost an inch.
 

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Two thoughts- first, you may still be working air out of the system. Second, a number of trucks (mine included) don't like the coolant mark. Mine runs about a half inch below. I can fill it to the line and it will be back down within a week. If I leave it alone, it will stay at the half inch down level for years. I gave up fighting it a long time ago.


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