Temp Guage and that sweet smell of coolant

[emt_hound]

Hi Everyone,

So I've read a lot about white smoke and smelling coolant in your exhaust as being a sign of a cracked block or (I think) blown gaskets.

I finally got the engine to turn over on thursday. I ran it again after completing its first oil change in years. I noticed that I get that sweet smell of coolant when the engine first cranks over but not after. I checked it twice. Definitely sweet smelling (at least from the driver's seat) when I turn the key but no smell when I stand by the exhaust with the Blazer idleing. What do you all think? I would assume with coolant entering the combustion chamber that I'd be smelling it in the exhaust all the time.

On a similar note, the temperature guage doesn't move when the engine is running, but as soon as I turn it off, the needle will move up to (I'm assuming) an accurate reading of the temp. I also checked this twice. The second time, after idling for 15 minutes or so, it pegged at operating temp...but only after I cut the engine.

Is this indicative of something or do I have a bum ground somewhere?

For what it's worth, the Blazer is definitely low on coolant. A/C and heat both work; the water pump looks fine (no visible leaks), and the hoses are in good-ish shape, but there is no coolant in the reserve tank. I intend to clean the radiator and do a coolant flush a little later on down the line.

[JetBoater]

I would check for coolant leaks on the engine. If you smell coolant from your drivers seat, one can assume it could come from a heater core, or other plumbing around the engine...check hoses and fittings.

If you had a 'tiny' leak into combustion chamber, it may not be noticeable. If you had a 'small' leak, you could possibly smell it and exhaust may or may not appear as a white cloud. Any significant leak would provide a large white cloud and you would be in danger of an engine hydraulic. My buddy went through 2 starters before he bump-started his 7.3 and bent a rod... due to a head gasket leak. He was going through coolant and had all the signs telling him not to drive it... oh well.

Your coolant gauge sounds like a wiring or ground issue. If the gauge works and shows normal when ignition is cut, then the sensor works and the gauge works... trace the wiring...and ensure you have a good ground and the feed wire is not grounding out somewhere as well.

Mechanical temp/oil pressure/volt gauges provide more accurate readings than factory idiot gauges, and are not expensive if you wanted to install one.

Good luck.

[Robyn]

A cracked head, bad head gasket or ?? other engine issue will manafest itself with high pressure in the cooling system and coolant blow over out the overflow tube.

Steam out the exhaust with a miss on startup is also possible symptom of head/gasket etc.

The gauge getting goofy after you turn it off is not an issue.

A hard top hose (real hard) and coolant pukeing out the overflow is the usual symptom of the head/gasket issue.

Check your floor area right under the Inside HVAC box for signs ofm coolant leaking down the firewall into the carpet padding.

If there is coolant leaking inside, then the issue is the Heater Core.


Missy

[emt_hound]

Thanks JetBoater and Missy,

Hmm...well, I sat in the truck with the engine off for about five minutes. No coolant smell.

I poked around under the hood. No visible leaking. No smell.

I turned over the engine. I got the sweet smell on the first waft of exhaust but then it went away. Also, no smoke, steam, or vapor.

I checked the hoses. No hardness. No visible coolant in the reserve tank at any point (neither hot nor cold). Top hose is hot on the bottom after running the engine...so I assume that means coolant is flowing. I'm also assuming since the reserve tank is always empty that I'm probably low.

I checked the passenger side carpet at the firewall. No dampness...no indication of a problem with the heater core. It was dark out, though, so I'll check more thoroughly tomorrow.

I guess this could just be one of those things. So far, it sounds like it isn't symptomatic of a gasket/head problem...which is letting me breath a little easier. ;)

[JohnC]

Be sure you bleed the thermostat housing. Air bubbles here can cause a lot of the issues you are seeing. If they keep coming back, well, the air has to come from somewhere...

[Robyn]

Get a helper to start the rig while you let your nose sample the exhaust.

Sweet odor from the tail pipe means that antifreeze is getting into the cylinder/s somewhere.

A small seep thats just starting is likely what your seeing at this point.

The coolant tank should have coolant up to the COLD mark when cold.

No fluid indicates that its going somewhere.

Probably a head or gasket issue just starting.

Sadly there is no easy "quick" fix.

Depending on the miles on the engine, I would plan on getting the heads off and having a look.

Could be a gasket, could be a cracked head.

The gaskets tend to go away around the watter passage at the front of the block where they join cyls 1 and 2

Cracks can form between the valves and have also been known to happen in other places.

What year rig ??

Fill in your signature area, then we can see more of what we are working on.

Missy

[emt_hound]

Hey Missy,

Okay, I found the signature line. I should have it from here on out. I have a 1994 K5 Blazer. I'm the guy stationed in North Africa with absolutely no access to anything except what I can get shipped here via military post office. :)

The truck's got 94k on the odometer and has been used and abused for several years (and it mostly sat outside for about six months) prior to me buying it at auction from the US Government here in North Africa. Coolant is definitely low but I finally got my hands on some Prestone coolant and will be flushing the system (hopefully) this week.

No doubt you're right that I'm seeing the signs of a problem developing. If it is a gasket or cracked head issue than there isn't too much I can do until my tour is complete and I can ship the rig back to the U.S. I don't think I have the tools or knowledge here to affect a repair. I'll keep reading, though.

Here's a follow-on question: I drove it today (6 miles) just to get the engine hot and give the transmission a chance to do something after sitting for so long (it's been broke down on the street for the last two months waiting on a PMD and a lift pump). Drove fine except once it was hot it would tend to fall into a rhythmic twitching at idle. Once I got it back to the driveway, I opened the hood. The engine was visibly thumping back and forth.

Under load, no visible/audible issues. At idle, the engine sort of rocks back and forth in a rhythm.

What do you think? Seems like every time I solve one problem, a new one appears (or becomes evident). I think I'd be completely lost if I didn't have this forum to read through.

[Robyn]

After the long "SIT" it could be a bad injector or ????

Ok this is a 6.5 turbo then.

The most probable issue is the head gaskets.

Both the heads are to be suspect at this point.

My bet is that there is degradation of the fire ring on the gasket around the front side of either number one or two cylinder.

This area is known to have issues. The coolant passage is in the head but not the block at this point and the coolant lays against the deck.

The head gasket fire ring is stainless steel and in combination with the Iron block and then add the coolant, you get some electrolysis that slowly eats away the the gasket ring and usually eats into the block deck too.

If the block is in good shape with no real errosion then a new gasket/s will solve the issue.

NEW HEAD BOLTS MUST BE USED as they are a one time use bolt.

If you decide to yank it apart, we can walk you through the procedure.

Not too tough to do.

Keep in mind the following.

The head bolts are to be replaced.
The pushrods must go back in just as they come out. The top and bottom ends are different. the end to the rocker is hardened and the bottom is not.

You can certainly get a gasket set (Felpro head sets) and new bolts shipped in.

Use RED or Orange high temp silicone goop on the Valve covers.

This is not a really big job.

Just be careful to plug/cap the injectors and pump when the lines are off.

Mark the lines in the pairs that they are in. Keep in pairs.

I use duct tape and write the numbers 1-3 5-7 for the sets on the LH side and 2-4 6-8 for the RH side

Make a map of the backside of the IP where the lines hook up.

You can leave the IP in place.

Pull the turbo, manifolds, both exhaust and the intake.

Get the hood off to allow room to sit in there.
Yank the fan shroud and the fan to afford room to crawl in and sit.

Once the air filter, turbo and manifolds are off, it gets fairly roomy in there.

The manifolds (exh) can be accessed easily by removing the front wheels and then the inner rubber flap.

The bolts are easy to get to at this point.

This stuff is all metric.

OH a box of 1 quart freezer zip lock bags and a felt pen are great helpers.

Place the various groups of bolts in individual bags, mark them and toss in the rear of the truck for safe keeping.

This makes reassembly a snap at a later date.

Keep us posted.


Missy

[emt_hound]

Oh boy, sounds like I've got some work cut out for me. :)

I'm still only catching a wiff of the coolant smell on start up with no smoke so I'm going to eliminate coolant leaks in the engine bay and then proceed deeper into the diagnosis.

The history of maintenance on the Blazer is completely unknown. I learn something new almost every time I crawl under it. For example, The oil hadn't been done in at least two or three years and the filter is even older than that. In this country, local mechanics (including our garage guys) generally don't replace the filters. Here's another example: I flushed the radiator today. I pulled out a faint remnant of the original coolant and a whole bunch of rusty water. That's what they'd been filling the radiator with: water from the hose. I amazed the radiator isn't eaten through. Final example: the Blazer is currently sitting on a set of dryrotted 235/85R16's. It looks like a bull on ice skates. Nobody knows where they came from, but I know where they're going. :D There's a rumor that a little store has Michelin tires in a town about 30 miles north of here. They say he caters to the neveau-riche with their Land Cruisers (big status symbol among the elite here). Michelins aren't my favorite but they're a name brand and they're new. With any luck, I can snag a set of 265/75's.

Speaking of the radiator, I pulled not one, not two, but three mummified birds out of it today. Gross. I don't think this poor truck has even seen any love.

I've got fresh glow plugs and injectors coming. Both need to be done given the odometer and condition of the engine bay. I'm hoping that, afterwards, replacing the injectors will help eliminate the engine rocking I'm getting when the engine's hot and idling. If not, I'll start looking at the engine mounts or harmonic balancer.

I look forward to going through all the pain of replacing the right side bank of injectors. It looks...er, difficult.

Two quick questions: First, anybody got an opinion on the engine rocking at idle (only after warming all the way up)? The engine sort of cha-cha's back and forth like an unbalanced washer. There is no noticable rocking when the engine's under load.

Second, when I changed the coolant today, I took off the top radiator hose where it connected at the thermostat housing, siphoned out all the crap from the radiator with some tubing and a hand pump. I filled and siphoned three more times with hose water until the siphon was pulling clean water out, and then I filled the radiator with a mix of 50/50 Brita filter water and Prestone (no distilled water here). I reconnected the hose when fluid started to run out of the thermostat housing (which I wasn't expecting). I had the overflow tank cap off and I ran the engine for about fifteen minutes with the heat on high. The cabin heat seemed to work fine and the fluid level in the overflow tank rose steadily. After I let it cool a few hours, I noted that the overflow tank showed that it was at full cold (so no fluid needed).

My question is: did I miss something? That seemed way too easy to burp air out of the system.

[16gaSxS]

Something else to check is your water pump. When I did my up grade on my '95 I put an new pump on and timing gears and chain. After 30 days the pump start to leak very small amounts of coolant out the center shaft seal. It was very hard to find and took me about 3 weeks to pin it down I kept it at the cold mark. Also not sure about Government version but the civilian 6.5 uses Dexa Cool not the Green Preston they DO NOT MIX.

[emt_hound]

I'll keep an eye on it.

As for the Prestone, I don't have much choice. It was the only thing I could get my hands on. I was able to get four one-gallon bottles and there isn't likely to be any more coming. I used 1.5 gallons this time. I'm planning to get a new thermostat and then flushing it out again so there shouldn't be too much mixing...although what I pulled out of the radiator today definitely wasn't Dex-cool. It was more like rusty water.

I'm more concerned about the engine rocking back and forth at idle after warm up. I've tried searching the threads but haven't found anything quite on point.