Jump to content
Sign in to follow this  
ProJect

How hot does your L20B exhaust manifold get?

Recommended Posts

Hello! 

 

I have been having issues with overheating. After replacing the thermostat and draining the system, it still overheats(according to the gauge in the dash) when it stays over 2500rpm for even a few minutes. I took an infrared thermometer to the exhaust manifold and it read 550* or so. This doesn't seem crazy hot, so maybe my gauge is broken? Im just seeing if one of you l20b owners could check your manifold temp when it's warmed up and let me know. I'd really appreciate it!

Share this post


Link to post

Have you any recent work done to your engine? Is the fan put on the correct way? Are your belts tight and the water pump turning? What colour was the old coolant when drained? Are the radiator fins plugged? Has the thermostat been installed properly?

 

Use the infrared not on the manifold but on the upper and lower radiator tanks. There should be a noticeable difference of about 10~15 degrees, if all's working well between the two. 

 

Compare your reading of the radiators hottest temperature and see if the gauge is the same.

 

If not, then we can determine if your problem exists else where.

  • Thanks 1

Share this post


Link to post

The exhaust temp isn't really related to how hot the engine runs. 550F seems reasonable. Exhaust can exceed 1,200F but this is exceptional and dangerous.

 

Shoot the thermostat housing with an infra red 'heat gun'. This is the water temp allowed by the thermostat setting. 

 

 

Define 'over heating'. Your gauge has a 'run range' marked. If the needle is in this range you should be ok but generally at the 1/2 to 2/3 of this range is normal. If it was about 1/2-2/3 but started running hotter this would indicate a change from normal that should be looked at.

 

Over heating is either lack of air or lack of coolant flow to shed or draw away excess heat.

 

Lack of air...

Rad fins missing or plugged with bugs, leaves or mud.

Fan damaged

Fan shroud missing. Shrouds improve fan efficiency

Fog lights, emblems, license plate or bug screen blocking air flow.

Belt loose.

 

Lack of coolant flow..

Low coolant level. Install a coolant recovery tank to the over flow tube. Need special rad cap for this.

Fan belt loose.

Heater hoses joined together in a closed loop because heater leaking. Never do this without blocking any flow through them.

Block full of rust and scale. Needs to be flushed with the drain plugs removed.

Rad tubes plugged or restricted by hard water calcium deposits. AKA 'boiler scale'. Use distilled water, and to top up

Soft lower rad hose that collapses from water pump suction when revved up.

Thermostat too hot. 180-185 F should do. Even new one can be bad in the box. Get $10 one not WallMart $2.99 special.

Always use water/antifreeze mix.

 

 

Other...

Gauge is wrong

Sender is wrong.

Head gasket ready to blow... does water spit out the overflow tube? Always needs topping up?

Severely retarded ignition timing.

 

  • Thanks 1

Share this post


Link to post

Thank you guys, this is the first time I've dealt with the cooling system, so you two have given me a lot to troubleshoot. Belt, fans, fins all good. I did have my heater break and my neighbor bypassed it for me(so now heat is always on, but maybe there's a kink in the line or something?). Luckily no spitting, the old coolant was cloudy and dirty and didn't separate or look like there was oil slick on top, but the distilled water i flushed it with looks good. It had been in there for easily a decade(the car hadn't been used much). Today I was driving and it went from 1/2 to full while not at high rpms, then right back down in a matter of about 10 seconds, which seemed odd. Belt's good, fan and shroud good, front license plate is interior on the dash, no emblems. When i say overheating, it'll steadily go up until i shut it off before it hits the red. It'll go down if i keep under 2.5k rpm I'm gonna trouble shoot everything mentioned above that i haven't already. I really appreciate you and the community as a whole.

Share this post


Link to post

So, since the weird up & down the other day, I haven't had an issue! I think that was maybe a clog that finally broke through. Luckily, I only had distilled water and some coolant system cleaner in there, so i didn't waste a bunch of coolant.

 

Quick question: should I flush again with more detergent and distilled water before i add new coolant? When i add new coolant, should i add a stop leak since it had been neglected so long?

 

Thanks again!

Share this post


Link to post
2 hours ago, ProJect said:

So, since the weird up & down the other day, I haven't had an issue! I think that was maybe a clog that finally broke through. Luckily, I only had distilled water and some coolant system cleaner in there, so i didn't waste a bunch of coolant.

 

Quick question: should I flush again with more detergent and distilled water before i add new coolant? When i add new coolant, should i add a stop leak since it had been neglected so long?

 

Thanks again!

What ever you do dont add stop leak... it makes more of a mess inside then it helps..

 

I would flush it again if it was me... cant hurt.....

 

And it honestly sounds like you thermostat was getting stuck..

So I would still check that.....

Edited by Crashtd420
  • Thanks 1

Share this post


Link to post

Thermostat was replaced recently. I'll keep an eye on it because i hear they are frequently bad out of the box, too. I'll do another flush and then fill her up! Guess I'll return the stop leak. Thank you, i was waiting on a reply to continue(well, not waiting, just working on other things and cleaning). I think we can close this case for now, i appreciate everyone's help!

Share this post


Link to post
1 minute ago, ProJect said:

Thermostat was replaced recently. I'll keep an eye on it because i hear they are frequently bad out of the box, too. I'll do another flush and then fill her up! Guess I'll return the stop leak. Thank you, i was waiting on a reply to continue(well, not waiting, just working on other things and cleaning). I think we can close this case for now, i appreciate everyone's help!

When your flushing it are you doing it with a garden hose and removing lines from the engine?

I like to do it in reverse especially through the heater core and radiator....

Share this post


Link to post
11 minutes ago, ProJect said:

Thermostat was replaced recently. I'll keep an eye on it because i hear they are frequently bad out of the box, too. I'll do another flush and then fill her up! Guess I'll return the stop leak. Thank you, i was waiting on a reply to continue(well, not waiting, just working on other things and cleaning). I think we can close this case for now, i appreciate everyone's help!

 

A replaced thing is an unknown thing. New is no guarantee it will work perfectly.

 

You can use a garden hose for water, doesn't have to be distilled for flushing, and a hose will agitate better with 40 PSI.  There is a brass drain on both? sides of the block near the rear that can be easily unscrewed to let rusty crap flush out. It's about level with the bottoms of the cylinders and as low as the coolant reaches. You can hold the hose up to it and flush forward or to the other side. Definitely remove the bottom rad hose at the engine end. Trying to twist off an old hose on the rad can tear the fitting off. Try not to ever remove them unless replacing them and then ... CUT them off.

  • Thanks 1

Share this post


Link to post

Thank you, datzenmike! I'll be doing that in the morning.

Share this post


Link to post

My first question would be do you have the coolant bypass hose in your thermostat housing on your L20b or did you use your L16 thermostat housing on your L20b?

 

  • Like 1

Share this post


Link to post

 For the temp sender to spike there must be circulation of hot water past it.

Share this post


Link to post
On 7/18/2019 at 3:07 PM, ProJect said:

I did have my heater break and my neighbor bypassed it for me (so now heat is always on, but maybe there's a kink in the line or something?). Luckily no spitting, the old coolant was cloudy and dirty and didn't separate or look like there was oil slick on top, but the distilled water i flushed it with looks good. It had been in there for easily a decade(the car hadn't been used much).

When you say, 'heater break and my neighbor bypassed it for me', I'm thinking the heater core inside the cabin, right? Where did your neighbour bypass the hoses? Cause if they did it correctly, you shouldn't be getting any heat at all in the cabin. 

Share this post


Link to post
On 7/18/2019 at 6:20 AM, datzenmike said:

The exhaust temp isn't really related to how hot the engine runs. 550F seems reasonable. Exhaust can exceed 1,200F but this is exceptional and dangerous.

 

Shoot the thermostat housing with an infra red 'heat gun'. This is the water temp allowed by the thermostat setting. 

 

 

Define 'over heating'. Your gauge has a 'run range' marked. If the needle is in this range you should be ok but generally at the 1/2 to 2/3 of this range is normal. If it was about 1/2-2/3 but started running hotter this would indicate a change from normal that should be looked at.

 

Over heating is either lack of air or lack of coolant flow to shed or draw away excess heat.

 

Lack of air...

Rad fins missing or plugged with bugs, leaves or mud.

Fan damaged

Fan shroud missing. Shrouds improve fan efficiency

Fog lights, emblems, license plate or bug screen blocking air flow.

Belt loose.

 

Lack of coolant flow..

Low coolant level. Install a coolant recovery tank to the over flow tube. Need special rad cap for this.

Fan belt loose.

Heater hoses joined together in a closed loop because heater leaking. Never do this without blocking any flow through them.

Block full of rust and scale. Needs to be flushed with the drain plugs removed.

Rad tubes plugged or restricted by hard water calcium deposits. AKA 'boiler scale'. Use distilled water, and to top up

Soft lower rad hose that collapses from water pump suction when revved up.

Thermostat too hot. 180-185 F should do. Even new one can be bad in the box. Get $10 one not WallMart $2.99 special.

Always use water/antifreeze mix.

 

 

Other...

Gauge is wrong

Sender is wrong.

Head gasket ready to blow... does water spit out the overflow tube? Always needs topping up?

Severely retarded ignition timing.

 

 

Looping the heater hoses together allows hot water from the head to circulate directly back into the hot engine and by pass the rad. Always close them off just like the shut off valve on the heater when not in use.

Share this post


Link to post
On 7/17/2019 at 10:56 PM, ProJect said:

Hello! 

 

I have been having issues with overheating. After replacing the thermostat and draining the system, it still overheats(according to the gauge in the dash) when it stays over 2500rpm for even a few minutes. I took an infrared thermometer to the exhaust manifold and it read 550* or so. This doesn't seem crazy hot, so maybe my gauge is broken? Im just seeing if one of you l20b owners could check your manifold temp when it's warmed up and let me know. I'd really appreciate it!

 

 

Keep in mind that this is a gauge reading with no hard numbers and an infra red reading of the exhaust manifold which has nothing to do with real engine temperatures. My L20B reads more consistently just above 1/2 way on the marked 'run range'  spring and fall than it does in the heat of the summer where it can wander a needle width or so higher.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.