What did I break? Huge coolant loss after trying to clean egr port

Hello members,

I am chasing an EGR code on my 95 SC Riviera.  I finally tried to remove and clean my throttle body to get to the EGR ports, with the hope that cleaning them would get rid of the P0401 insufficient EGR code.   I was unable to get the throttle body off, since there appears to be yet another bracket/bold/stud underneath and near the firewall of the car.  I tried to get the throttle body loose, but it was apparent it was not going to come off.  As an alternative, I pulled the EGR and EGR line and cleaned the intake port with a speedometer cable.  I reassembled everything and cleared the code.

I lost some coolant during the operation, which I figured was normal, so I poured more in.  Today, however, I overheated and my overflow tank had no coolant.

Did I break my throttle body?  It's of course possible the leak coincidentally occurred somewhere else, but Occam's Razor and Murphy's law says I broke something when I tried to pull off the throttle body.

Thoughts?  Also, if someone knows, how many bolts/studs/nuts hold on the throttle body?  I fear I will be pulling it.

Thank you.

Where is the coolant going?  Is it leaking on the ground or is it going in the engine?  If you don't see the leak I would check your oil to make sure it isn't milky.  If the oil is milky, don't drive the car until you change the oil and fix your leak otherwise you will ruin your engine.  I would remove the throttle body again and make sure you are getting a good seal.

My hunch is you have another problem causing coolant loss, a coincidence to your difficulties pulling the TB.

I have not figured out why you found pulling the TB to be so tough, but I drive a 98 not a 95, maybe they are that different. I do recall that the fastening bolts on mine were not all the same and the one in back near firewall was hard to reach. But I don't remember what the difference was.

Lets look at these one by each.

EGR

If your current EGR is an inexpensive replacement, say a Standard T-series (not a Blue Streak) you probably need to just replace it. The low line replacement EGRs such as the Standard T only last a couple years, in my experience, I've already posted about that. I've gone through 2 of them.

In any event, not only check the air passages to and from the EGR but also the air passages associated with the IAC. If your IAC is really gummy you may want to replace it rather than clean it/reinstall (throttle body cleaner will work to clean the IAC pintle and air passages). It is best, I think, to clean the IAC air passages with the TB off the car. When my tach flutters a little at idle I know it's time for TB service (it's been every 3 years or so; I have driven this car for 18 years).

If you replace the EGR, suggest you find a Delphi. Or a Delco (the OE one preferably).

I've only replaced my IAC once; after 3-4 (I forget) cleanings it didn't want to behave so I got one from (gasp) Autozone. Works fine.

COOLANT

You will likely need to remove the TB and replace the gasket. Reason: They tend to get a bit gummy and adhere to the TB and intake, then tear when disturbed. Just. Replace. It. The Victor Reinz version lists for about $5.50 only.

Coolant issues i have had over the years have included failed radiator cap (use a 16 lb one), a crack in a plastic side-tank on the radiator that wizzed coolant onto the ground -- it took me more than a year to find that I kid you not, because it didn't leak much and it didn't hit anything in the engine compartment (I used UV dye), and an issue with the overflow bottle (the hose to it). I have heard of lower intake manifold and thermostat housing concerns, apart from blown head gaskets (usually there is a problem that leads to the head gasket blowing, they don't just go).

If I had your car ATM I'd probably be stumped. Don't panic and good luck. I hope you have a factory service manual, it will save you **hours** not to mention headaches. Keep us posted.

David Jennings wrote:

Hello members,

I am chasing an EGR code on my 95 SC Riviera.  I finally tried to remove and clean my throttle body to get to the EGR ports, with the hope that cleaning them would get rid of the P0401 insufficient EGR code.   I was unable to get the throttle body off, since there appears to be yet another bracket/bold/stud underneath and near the firewall of the car.  I tried to get the throttle body loose, but it was apparent it was not going to come off.  As an alternative, I pulled the EGR and EGR line and cleaned the intake port with a speedometer cable.  I reassembled everything and cleared the code.

I lost some coolant during the operation, which I figured was normal, so I poured more in.  Today, however, I overheated and my overflow tank had no coolant.

Did I break my throttle body?  It's of course possible the leak coincidentally occurred somewhere else, but Occam's Razor and Murphy's law says I broke something when I tried to pull off the throttle body.

Thoughts?  Also, if someone knows, how many bolts/studs/nuts hold on the throttle body?  I fear I will be pulling it.

Thank you.

Thank you for the information.  I have to fix an old BMW today before I turn my attention to the Riviera.  With regard to the EGR, I did replace it.  In fact, I bought yet another one, of higher quality, and plan to replace it again once I find the coolant leak.  I did purchase another TB gasket.  This time, I will be take it all the way off.  I will let you know what I find.

I do have a factory manual, but I need a college course to figure out how to use it.  Great for troubleshooting; not much on diagrams and disassembly.

David Jennings wrote:

Thank you for the information.  I have to fix an old BMW today before I turn my attention to the Riviera.  With regard to the EGR, I did replace it.  In fact, I bought yet another one, of higher quality, and plan to replace it again once I find the coolant leak.  I did purchase another TB gasket.  This time, I will be take it all the way off.  I will let you know what I find.

I do have a factory manual, but I need a college course to figure out how to use it.  Great for troubleshooting; not much on diagrams and disassembly.

In the past I have used fluorescent dye to find collant leaks. Except for that radiator tank crack it's worked for me. BY THE WAY, I just remembered; one quirk with the Riviera is when you cange coolant you have to use "stop-leak" tablets for various reasons in the new coolant. They basically are walnut shells and ginger, ground up and smashed into tablets about the size of peppermint puffs. It's in the factory manual.

I am a little surprised that you find the factory manual lacks diagrams. One thing that surprised me about my Riv is the three-volume set they call the factory manual.

I wonder if your heater core is leaking. Rare, bu it can happen. Although I think you'd really know it, were that the case.

Albertj

Learned a couple things yesterday.  No apparent leak near the throttle body.  No cream in the oil.  Coolant was very low, so I filled it with distilled water and ran the car with the radiator cap off until it warmed up.  No sputtering or gasses escaping.  I have a leak, but as suggested, it has been there for a while, and it was a coincidence that it overheated after I worked on the throttle body.  I plan to replace the radiator cap and the thermostat (though the top hose is warming up).  Coolant is going some place. Would a slow leak in the intake manifold have this effect?  I have heard the manifolds leak on the 95's.  Thanks again. Got my fingers crossed that it's something external, not the head gasket. But even then, a head gasket is just my labor.

If your manifold & head gasket on the '95 have not been replaced, frankly, I think other '95 owners on this list would agree that you go ahead and do that anyway (I have a '98, no such issue ATM).  

Again, on my car I had a crackand pinhole leak in one radiator tank (the drivers side) and I kid you not, it squirted the fluid onto the ground so I did not find the leak for a very, very, very long time.  Matter of fact when I DID find it it was because I was under the hood doing other troubleshooting.

When I discovered that I replaced radiator (Visteon), heater and rad hoses (Gates), thermostat (Stant 195F) and rad cap (also Stant).  That was at 195K mi I think, I have not had to talk to the cooling system since; come to think of it, it's about time for a coolant flush & fill.

Thanks again for the replies.  I replaced the thermostat and radiator cap and refilled the radiator and overflow tank.  After 100 miles, no loss of coolant.  This makes me wonder what happened.  My low coolant light never came on, and I can't tell if my electric fans are working.  I have a scanner that operates live, but it failed to show anything other than coolant temperature.   Somehow the engine lost coolant, but the overflow tank still had fluid showing.  No codes.  Thinking of replacing the low coolant sensor and perhaps the temperature switch for the fans.  Thanks.

David Jennings wrote:

Thanks again for the replies.  I replaced the thermostat and radiator cap and refilled the radiator and overflow tank.  After 100 miles, no loss of coolant.  This makes me wonder what happened.  My low coolant light never came on, and I can't tell if my electric fans are working.  I have a scanner that operates live, but it failed to show anything other than coolant temperature.   Somehow the engine lost coolant, but the overflow tank still had fluid showing.  No codes.  Thinking of replacing the low coolant sensor and perhaps the temperature switch for the fans.  Thanks.

What were the temps during your 100 mile cruise. What I am looking for is a sustained period hot enough for the thermostat to open and stay open. Also, how did the overflow tank level change (measurement before and after the cruise). What I am looking for is the OF tank level shoulda gone up. if not, then that part of the system is where you are losing coolant.

You could be out of trouble, though, with the rad cap and thermostat change. I wonder if the old stat was in backward.

Also, did you add stopleak tabs?

Albertj

Hello AlbertJ.  Yes, I did include a little radiator sealant in with the water and coolant.  I will continue to monitor the levels.  I have marked the coolant tank for both hot and cold measurements.   The temperature holds at 200 on the gauge, and at 195 on my scanner.

Hi David, your coolant leak got me investigating, well, coolant leaks. I thought it would be "fun" (it IS Friday afternoon coffee break) to list some things to rule out which are *unlikely* but match the pattern of: there's a leak -- now there's not -- WTH?

1) find and check the freeze plugs, they are listed in the factory service manual Engine section. They can "weep."
2) small crack in the heads that allows pressure to enter the cooling system when the car is stopped (see http://www.silveradosierra.com/vortec-5-3l-v8/massive-coolant-leak-t72009.html and/or http://www.gmtruckclub.com/forum/threads/mysterious-coolant-leak.10784/page-7) - this would be from a teeny crack in a cylinder wall that communicates into the water jacket and you might only get it when that cylinder stops under compression. However, I note you don't seem to have coolant in the oil so... we'll see... Don't know if anyone's seen this on the 3800 engine BUT...
3) You've already fixed the rad cap - on many cars it's really simply the &*#^$*@ rad cap. See https://www.youtube.com/watch?v=a7u2hFwXTXk, no kidding you might be done with this coolant leak issue for a good while.
4) You probably already saw these, I am tossing them in for "posterity" (or "posteriority" = a ten-dollar synonym for "buttheadedness"): https://www.google.com/search?rlz=1C1GGRV_enUS754US754&ei=jVaHWpmLH-HQjwSzqbLwCA&q=3800+coolant+leak+above+water+pump&oq=GM+constant++coolant+loss&gs_l=psy-ab.1.2.0i71k1l8.0.0.0.4985.0.0.0.0.0.0.0.0..0.0....0...1c..64.psy-ab..0.0.0....0.r1pvqID5EqA

Really you hopefully nailed it with the rad cap - good job!

Albertj

Friends,

I changed the oil yesterday and used the opportunity to inspect the engine and underside for coolant leaks.  I found some apparent coolant loss beneath the radiator shroud.  This, perhaps, could have been from the cap.  It could also be the radiator, I guess.  I will continue to monitor the loss.  I suspect,however, it is a gradual loss from the intake manifold.  

I checked the factory manuals, and removing the intake seems like a very doable job.  I suspect I will need to replace the throttle body gasket and maybe the SC gasket as well, though it would be great if I didn't have to remove the SC to pull the intake.

Thanks again.  

(Fingers crossed on the P0401 code, the original reason for this post.  Tried a higher quality EGR valve, and it seems to be working better.)

David Jennings wrote:

Friends,

I changed the oil yesterday and used the opportunity to inspect the engine and underside for coolant leaks.  I found some apparent coolant loss beneath the radiator shroud.  This, perhaps, could have been from the cap.  It could also be the radiator, I guess.  I will continue to monitor the loss.  I suspect,however, it is a gradual loss from the intake manifold.  

I checked the factory manuals, and removing the intake seems like a very doable job.  I suspect I will need to replace the throttle body gasket and maybe the SC gasket as well, though it would be great if I didn't have to remove the SC to pull the intake.

Thanks again.  

(Fingers crossed on the P0401 code, the original reason for this post.  Tried a higher quality EGR valve, and it seems to be working better.)

Your EGR drama's probably done for a good while, with a higher quality EGR valve installed.

When you remove the TB consider thoroughly cleaning the air passages in the intake where the TB mounts.  Also the air passages in the TB (remove and clean the IAC, being careful - for your convenience - not to move the pintle - or if you're flu$h, just replace the IAC and remember to get a good one like a Delphi).

Update on P401. No codes. Just goes to show that the cheapest part may not be the best.