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42K views 151 replies 13 participants last post by  ehall 
#1 · (Edited)
I have looked around and it seems that 1995 was the last DeVille with a 4.9 engine. Jasper wants $4k for their kit. remanufactured.com wants less than $2k. I suppose I can get a junkyard mystery motor to test with and see how hard it is to hook up my 4.1 intake. If it works then I'll look around for a hotrod reman.

I am going to autozone on Monday to buy intake manifold gaskets for my 85 4.1 and the 95 4.9 and see if the ports are way different.

Any other hints before I do that? Should I ask for parts from a different year or model than the '95 4.9 engine?
 
#109 ·
1226464 is the service replacement BCM. It is normally shipped without a prom. It fits several years and models. 1985 to 1988 if i remember correctly. It fits the Coupe and Sedan Gas 4.1 V8 and Diesel 4.3 V6. You will be ok with any of the 85 to 88 BCM's as long as you check to make sure the Prom number is the same. If not, Transfer your Prom from the original in your car to the new BCM. I have done this many times. (Especially since the Diesel BCM is EXTREMELY rare.)

Text Font Line Document
 
#110 · (Edited)
Battery was nicely recharged overnight so we gave it a shot. It wanted to catch but wouldn't. Figured out the distributor was off by a tooth so we turned it a position and it started right up.



As you can tell from the smoke we have some mechanical problems that are keeping us from running the engine for very long, so I don't have anything to report other than the fact that it starts and idles. The belt is pulling against the water pump housing and from what we can tell it looks like the crank pulley is too far inwards, so we are going to shim the crank pulley by 1/8th inch. It's also dumping power steering fluid so we can't run it for more than a minute without the pump starting to scream, and that needs to be fixed asap. All of the shop bays were tied up this morning so the owner will do the work this evening or tomorrow morning, and then I'll go back to dialing it in.

Just because it starts and idles doesn't mean it will run good, but it's definitely a step in the right direction.
 
#112 ·
Starting is good! I wish i had a video of me starting my 85 Gas Coupe for the first time. It had sat for a long time with a stripped distributor gear. When i did get it started, There where 2 sticking intake valves (Due to gummy gas i believe). I had the air cleaner off. The explosions could be heard several blocks away. Sounded like some sort of automatic weapon. The flames where shooting way into the sky (sic). It was a bit funny to see a car that was designed to be so quiet and smooth making co much of a racket!

by the way i could use a few parts off of the old 4100. I am building up a replacement engine for the above mentioned car. I have quite a loud main bearing thump and low oil pressure. I am using an Allante 4.1 short block as a starting point. (Roller cam followers) I just purchased a set of 4.5 Heads and am looking for a 4.5 Intake Manifold.

I am looking for an Oil Filter Adapter that mounts right behind the distributor. Also possibly the Air Diverter valve and pump. I have some on there way but until i get them i have no idea what condition they are in or if there is anything missing.

Good luck with he testing!
 
#114 ·
I am looking for an Oil Filter Adapter that mounts right behind the distributor. Also possibly the Air Diverter valve and pump.
I used the 4.1 oil filter adapter on my setup because it had the correct orientation for the existing cooler lines, and the 4.9 adapter fittings were just different enough. I think I saved the 4.9 adapter but don't know for sure, if you want that I will go look for it and let you have it for postage.

I haven't had any other claims on the smog pump tumor so it's yours if you need it.
 
#116 ·
I agree. I just finished replacing the trans on a 1989 Eldorado earlier this spring. Granted, this car had 193k on it so it's not completely uncalled for, but 2-3 clutch pack was completely gone - steel on steel discs, clutch material completely missing. In fact, I found a section of clutch disc in the pan, and I'm still perplexed as to how it got down there in one piece. Also, I'm pretty sure the trans in my current '90 was replaced at some point before I got it. Old boss's 1988 Deville? Trans replaced just over 100k.

However, outside of the occasional shift solenoid, I have neither experienced nor heard of many '91+ 4T60E's with problems. All 4T60E's I've owned have operated flawlessly regardless of age or mileage.

Don't neglect the fluid, avoid frequent low speed/high torque WOT downshifts and you should be ok.
 
#117 ·
The tranny guys I've talked to said not to worry about it. The torque converter is the same part number for the 4T60 and 4T60-E, and if they didn't beef the torque converter then it should hold alright. The only real "problem" I have with mine now is a hard downshift to 2nd when the tranny is still cold (it's butter after it's warmed up) which is fixable with a small part and $2000 in labor. Everything else on it works great. I keep the fluid fresh.
 
#118 ·
Wow you got it running! I've been watching your progress lately, congratulations! I think you're going to be happy with the performance of the bigger displacement. I will say this however, I had a GMC pickup years ago with the TBI, I like the PFI much better on my 93. Too bad there is so much different. Hmm, I wonder what you would need to change it to a PFI? I think you'll be fine with your setup tho. :thumbsup:
 
#119 ·
Did some more work on the car and got it to a point where I could drive it around. It drives wonderfully, there's a nice deep power well on it that's easy to tap. Still have a bunch of things on the to-do list though.

Yesterday I said the belt was riding on the back of the pulley and rubbing on the water pump housing and we concluded that the crank pulley was the problem. Today we brainstormed about it some and decided that it couldn't be the crank pulley, since it has a high enough torque that the bolt is forced to sit flush on the crank snout, and besides, all that stuff is original to the 4.9 block so none of it is different (not intentionally anyway). As a lark, we put a hardened washer in the crank pulley as a spacer, and with the bolt tightened down the belt does clear the water pump housing by a hair, but not a lot. Looking at things a bit more, I remembered that the water pump gasket was the thick fiber gasket that came with the AC Delco pump and not the thin paper type, and that may be contributing to the problem a little. Also, looking at the water pump pulley that I am using (which came from the donor 4.9) it appears that the belt has been riding off the rear of the pulley for a while, so maybe the stamped sheet metal pulley is just pulled in a bit and the belt is naturally riding off the back of it, which is worsened by the thick gasket. Long story short, we will try swapping on the pulley from my 4.1 tomorrow and see if the belt still gets sucked in towards the housing, if so we will look at replacing the water pump gasket with the thin paper style. As of right now, with the spacer in the crank pulley, the belt is not rubbing against the housing, but the crank pulley is free to walk in towards the snout so it might later.

Power steering leak was just the high-pressure fitting hadn't been tightened. Easy fix.

I had a vacuum leak in my cruise control, probably the vacuum switch on the brake pedal is holding the vent open but I don't care right now so I blocked off vacuum to the solenoid and will deal with it later. It's interesting how slowly the reservoir builds vacuum pressure. If I start the car then shut it off, some of the interior diaphragms get pissy and start flapping. The brake booster also takes a little longer to build up pressure.

Anyways once the vacuum leak was fixed I was able to set the ISC and TPS. I did it the simple way, removed the ISC from the car and drew the pintle back, then set the idle stop screw to 500 RPM while the ISC was still out of the car. Then I set the TPS to throttle angle zero so I could ignore all of the reference voltage crap, and then put the ISC back in the car and set the gap. It idles and runs good, and I have been having fun tearing up the highway by the shop in my tests.

I still need to set the base timing and replace the water pump pulley at the shop, and then can bring it home. I will fix all of the small little problems like cruise vacuum here.
 
#120 ·
Did some more work on the car and got it to a point where I could drive it around. It drives wonderfully, there's a nice deep power well on it that's easy to tap.

Yesterday I said the belt was riding on the back of the pulley and rubbing on the water pump housing and we concluded that the crank pulley was the problem. Today we brainstormed about it some and decided that it couldn't be the crank pulley, since it has a high enough torque that the bolt is forced to sit flush on the crank snout, and besides, all that stuff is original to the 4.9 block so none of it is different (not intentionally anyway). As a lark, we put a hardened washer in the crank pulley as a spacer, and with the bolt tightened down the belt does clear the water pump housing by a hair, but not a lot. Looking at things a bit more, I remembered that the water pump gasket was the thick fiber gasket that came with the AC Delco pump and not the thin paper type, and that may be contributing to the problem a little. Also, looking at the water pump pulley that I am using (which came from the donor 4.9) it appears that the belt has been riding off the rear of the pulley for a while, so maybe the stamped sheet metal pulley is just pulled in a bit and the belt is naturally riding off the back of it, which is worsened by the thick gasket. Long story short, we will try swapping on the pulley from my 4.1 tomorrow and see if the belt still gets sucked in towards the housing, if so we will look at replacing the water pump gasket with the thin paper style. As of right now, with the spacer in the crank pulley, the belt is not rubbing against the housing, but the crank pulley is free to walk in towards the snout so it might later.

It idles and runs good, and I have been having fun tearing up the highway by the shop in my tests.
Have you checked the difference in alternators? Can't remember if you said you are using the 4.1 mount or the 4.9 alt. mount. Maybe the pulley on the 4.1 alternator isn't out as far as the 4.9. ???

Heheh got more power eh. :lol: I have no complaints about my 4.9 in the power department, definately will make the tires scream blood curdling hell breaking loose. :lildevil:
 
#121 ·
The top pulleys seem fine. The other possibility that we are considering is that the old AC compressor may be off a little, since it's the only thing that isn't from the 4.9
 
#122 ·
We've decided that the water pump housing is probably deformed. I have a digital angle finder around here somewhere and will check it out.

We tried setting the base timing to 12 degrees but the engine had some miss and stumble issues under load. I reset base timing to 14 degrees and now it only has a little bit of flutter when I'm cruising around 55 MPH. It feels like a car that needs a tune-up. I sliced into one of the plug wires somehow and I think I only went into the insulation but I may have cut the core. I kept my Accel 8.8 plug wires and will probably try swapping one or all of those at some point to see if it ignition is cleaned up. It's also possible that fuel isn't getting delivered properly but symptoms suggest otherwise--I can stomp on it and get solid burn, and the O2 output on the diag shows fluctuation between rich and lean as the engine maintains balance--but I will keep an open mind. It's also possible that I have a vacuum problem and/or EGR is not working correctly, these are other things I will have to look into.

Anyways the car is back home and just needs this kind of minor attention. Otherwise it's drivable and fine. I'm willing to declare the project a tentative success at this point but won't know for certain until I get the bugs squashed.
 
#123 · (Edited)
In thinking about your project i had the thought. The one sensor that may give you the most trouble with a false signal to the ecm would be the MAP sensor. By changing the Volumetric Efficiency of the engine relative to what the ECM expects. The map sensors signal will be quite a bit different than what the 4.1 reported. The MAP sensor modifies the Timing quite a bit. If you are having drivability issues with the base timing set according to spec, I submit the problem may be that the MAP is reporting a signal that the ECM is interpreting incorrectly. This may be advancing the timing incorrectly. I am not sure how to correct this without modifying the MAP tables in the prom. Possibly playing with the base timing will allow smooth operation? Maybe a MAP sensor with a different output curve? (If one is available) Anyone else?

I am sure there will be a fair amount of tweaking to get things running to your satisfaction. Good luck and keep us informed.
 
#124 ·
Final recipe:

4.9 block and heads
4.5 TBI intake manifold
4.5 TBI throttle body
Chevy 305 TBI injectors
4.1 sensors (for computer compatibility)
4.1 ignition parts (for computer compatibility)
4.5/4.9 front exhaust manifold, 4.1 rear exhaust manifold, 4.1 crossover and intermediate pipes (may be able to use 4.5 TBI pipes everywhere)
4.5/4.9 alternator bracket
mix-n-match other parts as needed or desired
 
#126 ·
My thinking on the MAP sensor is as follows.

The 4.1 is notorious for not having much manifold vacuum. This is reinforced by the fact that Cadillac saw fit to install an electric Vacuum pump.

The 4.9 is known to have a lot more vacuum and does not have the added electric pump.

This would indicate to me that the 2 engines have a radical different manifold vacuum profile through the power range.

Where as the oxygen sensor will compensate for variations in mixture, MAP is normally a set factor in the design of the engine management firmware.

MAP is used as one of the primary signals along with RPM to set the correct ignition timing. (Ref an old mechanical distributor with both centrifugal and vacuum advance mechanisms)
Manifold absolute pressure is an excellent way to determine engine work load.

I wonder if this becomes an issue whether or not someone on one of the early GM ODB1 tuning sites could be of help.

This may not be an issue as careful adjustment and tuning of the engine timing may be enough for the OP to be happy with the results.
 
#127 ·
The map sensor has it's own vacuum line and sees engine vacuum immediately. This is true for a couple of other systems that need to monitor engine vacuum directly, such as the transmission and the fuel system The reservoir is only used with systems that need stable vacuum sources, such as cabin HVAC and cruise control (and the booster has its own reservoir), which suffer from fluctuating vacuum.

FWIW the 4.1 only used the pump to feed the cabin, cruise, and brake booster vacuum circuits, so basically the pump just replaced the reservoir for the systems that need stable vacuum pressure. The pump is better than the reservoir since it provides immediate constant vacuum pressure. I'm sure it was deleted to save money, not because of better vacuum in the later years (possible but unlikely--the 4.1 produced 15-20 hg inches the same as every other engine).

Sometimes a vacuum leak on one circuit will affect another circuit, since it allows the manifold vacuum pressure to drop, so it may be the source of my uneven combustion at speed, but that's about as far as it goes.
 
#128 · (Edited)
I think I tracked the stumble to a vacuum leak at the EGR solenoid.

edit--there was also a small leak at the rubber connector for the tranny vacuum modulator and it expanded out when the engine got warm. I think the modulator itself also needs to be replaced
 
#129 ·
Just a thought. An adjustable modulator valve (if available) would give you the ability to tune the transmission to your new engine and driving preferences. The modulator on your THM440-T4 transmission controls the shift firmness. The cable controls the shift point.

Hope all is progressing well.
 
#130 ·
I sent some of the oil from my 4.1 to Blackstone for a follow-up analysis. In the 16k miles since the previous analysis, potassium parts-per-million went from 14 to 30, and sodium went from 17 to 48. These are indicators of a coolant leak and it was getting worse. Since I had replaced the throttle body and intake gasket in between those tests, it's pretty clear that the old 4.1 was working up to a full-blown head gasket leak. So it's a good thing I replaced the engine.

I should have replaced the trans too. My trans is slipping when shifting from 2nd to 3rd and slipping all the time in 3rd now, after about 60 miles of driving on the new engine. I have replaced the vacuum modulator and clamped the vacuum lines (which did fix some other problems), and I've adjusted the TV cable about 20 times, so there's no getting around it the tranny internals need some work. I'm pretty mad since I was told by two different independent tranny shops to leave it alone... now I have to pull everything back out to do the rebuild we could have done while the engine was already out. I am going to do a couple of other things as last-gasp efforts but otherwise I expect to need a rebuild and won't be doing anything more on it for a while.
 
#132 ·
You might try disconnecting the modulator valve vacuum line. This will cause the transmission pump to go to full pressure all of the time. This will cause a maximum firm shift. The see if the trans still slips. Unfortunately you probably have a toasted trans. I have seen quite a few 440T4's available with low miles since rebuild. People have there trans go bad, Get it rebuilt, and have there engine fail shortly thereafter. They get flustered with the cost and scrap the car. Maybe you could get lucky and find one of these. I also hear that they are not to difficult to rebuild with a kit.

I had a similar experience with my Diesel. I rebuilt the engine only to find that my trans went out within 10 miles of the engine replacement. Talk about frustration! I was lucky enough to find one in a local wrecking yard that had just been rebuilt. (GM Rebuild) This was lucky as the diesel 440-T4 is extremely rare.

The transmission is easier and much less costly to R & R than the engine. A local shop only charged me $200 to do the swap. I do however live in an area where labour rates are low.
 
#133 ·
Sorry for leaving this hanging but I had to go out of town and do some other stuff. Anyways I've been doing some more testing and research and my guess is that the transmission probably just needs some cleanup and adjustments.

First of all, disconnecting the modulator does produce complete (harsh) shifts with no slipping, which indicates that the clutches are alright and the slipping is probably due to the long slow shifts that never fully complete. Second, I noticed that the car was slipping a little when we did the first test runs right after the swap, and the problem with constant slipping came on strong after I fixed the two vacuum leaks. Both of these factors suggest that there is too much vacuum pressure at the modulator that is interfering with fluid pressure for the shifts.

However I have measured vacuum at the modulator inlet and it is a little higher than recommended, maybe 18ish at full warm idle, but that should not be too high. I replaced the modulator a week or two back and that did not change anything. It was an adjustable modulator from NAPA, and I have turned the screw as far as it wants to go and that has not had any effect either. So either the new modulator is bad or there is some other contributing problem. I will probably go buy a cheapo adjustable unit at autozone and see if it will work any better.

I have also bought a new TV cable (found an aftermarket on ebay) but have not figured out how to install it yet. The FSM says to just pull the cable up through the opening but I can't seem to get it that far.

So that's where things stand. My work project came to a sudden stop so I am going to have to slow down on this for a bit but will try these two things as soon as I can get around to it. These hydraulic trannies use fluid pressure for everything and a little bit of variance in the inputs can cause a lot of change in the outputs. I am longing for solenoids I can tell you that.
 
#134 ·
You may want to put the vacuum gauge back on and see if and how much the vacuum drops when the car accelerates. It should drop off pretty quickly. I am wondering if the correct port is being used on the throttle body (If this is even possible). The lower the vacuum the higher the pump pressure in the trans. The higher the vacuum the lower the pump pressure and softer the shift. The modulator valve connects directly to the pump offset to control pressure. It is the only input that controls the overall pump pressure. It is also possible that the pump is worn. At worst a rebuild kit would probably fix it. Maybe a new pump.

When we talked a while ago you said you had an oil filter mounting adapter from a 4.9. You said the oil cooler lines where different. Are they bigger? I wonder if they increased the size of the lines to improve oil flow. Anyway i could use one. If you are so inclined let me know how much you want for it.

Have a great day!

PS: When you replaced the modulator valve was it for the 85. I wonder if the 85 4.1 modulator is calibrated different then the 89 4.5. The part numbers are different. The 4.1 and 4.5 engines have a different vacuum curve under power. Maybe?
 
#135 ·
I have watched the vacuum and it does move around quite a bit, but the tranny chapter in the FSM says you need to monitor vacuum and fluid pressure at specific RPMs and I'm not really setup for all that. I have confirmed vacuum specs in ALLDATA for 92 Deville and 85 Deville are the same basic range so I should be okay there. I have been reading a lot on the other GM forums and they all say that tweaking the modulator should make a big difference but it doesn't make hardly any difference. All of the different modulator brands appear to be the same unit just different label on the box--they are "universal" for the 440 and 4T60 and so on, just different fittings on the end depending on the year. I suspect there is something else going on. Fluid levels are fine and the filter and fluid was refreshed a couple of years ago. The TV cable might have been stretched out. We replaced the input seal so maybe something went wrong there. It's possible that I have made some stupid mistake or that the replacement modulator is damaged or something like that but honestly I think I need to take it to a pro and ask them to put their gauges on it and go from there.

I exchanged some PMs with edahall about his 4.1->4.9 swap and the shift kit stuff. He said he did it because he wanted to not because he needed to.

On the OFA, the fittings look like the same thread (different fittings same thread) but they are positioned different so they will not mate to existing lines. I have not looked for it yet, PM with the details and we'll figure something out .
 
#136 · (Edited)
I reinstalled my Accel 8.8 wires to see if it made a difference on anything, and the engine smoothed right out, and also killed some engine noise. These replaced a brand new set of Belden wires (admittedly one of them had a nick in the insulation), and this is the second time I've had this result. I've used those Beldens on other cars with good results but they don't seem to work very well on the Cadillac.
 
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